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Gemstones
Welcome to Twin-Diamonds Gemological Education Center and Guidance
to Gemstones, Diamonds & Jewelry
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Diamond Diamond is
carbon in its most concentrated form.
Except for trace impurities like boron and nitrogen, Diamond Diamond is
composed solely of carbon, the chemical element that is fundamental
to all life.
But Diamond Diamond is
distinctly different from its close cousins the common mineral
graphite and lonsdaleite, both of which are also composed of
carbon. Why is Diamond Diamondthe
hardest surface known while graphite is exceedingly soft?
Why is Diamond Diamond transparent
while graphite is opaque and metallic black?
What is it that makes Diamond Diamond so
unique?
The key to these questions lie in Diamond Diamond's particular
arrangement of carbon atoms or its crystal structure the feature
that defines any mineral's fundamental properties. A crystal
is a solid body formed from the bonding of atomic elements
or compounds in a repeating arrangement. Often, crystals possess
smooth external faces.
Due to their symmetrical and finite nature, the building blocks
of crystals are limited to relatively small numbers of atoms,
and their chemical compositions to simple numerical combinations
of elements.
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The Emerald is
a green members of the popular beryl family of minerals. The
green color occurs when pure, clear beryl contains either chromium
or vanadium.
Emerald Colombian
Emeralds are among the world's most beautiful,
with rich grass-green coloring that's often kissed
with a touch of blue. Quality Emerald are
also found in India, South Africa, Afghanistan,
Pakistan, Russia, and Zimbabwe. Recent finds
in North Carolina may provide us with quality Emerald if
the mine continues to produce stones.
Emerald are
traditionally thought to enhance the clairvoyance of their
wearers.
Egyptian Emerald were
introduced to the world about 4,000 years ago, but the stones
from those mines are a duller green and are not considered
high quality by today's standards. Mummies were often buried
with Emerald .
The gemstones were
also popular in ancient Rome.
Traditionally, Emerald are
worn to promote healing and enhance love and contentment.
Emerald is
the birthstone for the month May.
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Fossilized Dinosaur Bone
These fossilized Dinosaur Bones from Montana have been shaped
and polished to create attractive Cabochons. Each Cab is opaque
in a brownish-Red body color with Black veining.
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Glass
Glass, by virtue of its wide range of color and low cost, has
been used for centuries to imitate natural gemstones. It is
easy to identify by its R.I., spherical gas bubbles, swirled
growth pattens, and characteristic strain lines seen between
crossed polarizing filters.
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Golden Sapphire
Golden Sapphires are
intense, bright stones ranging from medium light Yellow to
deep golden Yellow. Our faceted Gems are
exceptional in jewelry and
have become quite popular as an alternative color for Blue
for those with September birthdays.
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Goshenite Beryl
Goshenite is the Colorless Beryl which may have a very slight
tint of Blue or Silver. This transparent, faceted Gem is an
inexpensive choice for jewelry Goshenite
is found in Brazil and the U.S.
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Green Sapphire
These Sapphires range
in tone from yellowish Green to bluish Green to grayish Green.
They are not the same tone of Green as the Chrome Tourmaline,
Tsavorite Garnet or Emerald.
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Green Spodumene
The most recognized member of the Spodumene mineral group is
Kunzite. But this group also includes the rare Hiddenite, Green
Spodumene and Yellow Spodumene. Hiddenite is especially difficult
to locate in the markets, and Green and Yellow Spodumene are
also hard to find.
Spodumenes have a hardness of 6.5-7.5. Its crystals grow in
the monoclinic system as flat, jagged prisms. Since Spodumene
has perfect cleavage, it is a very difficult Gem to facet.
This vibrant mineral was named for the Greek spodumenos, meaning "burnt
to ashes," a reference to the Gray color of the nonGem
crystals
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Green Tourmaline
Green Tourmaline is the most recognized of the Tourmaline colors.
The primary source for this color is Brazil, but Africa, Afghanistan,
Maine and California also produce beautiful Green Gems. Green
Tourmalines are typically eye clean stones. Most are cut in
the rectangular shapes due to the crystal growth and the pleochroism.
Shades range from a pastel Green to a deep, vibrant Green.
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Grossular Garnet
The Grossular Garnet species incorporates many colors: Colorless,
Yellow, Green, Orange, Brown, Pink and Black. Of course there
are many variations and shades of these colors. Pure Grossular
is Colorless; the various colors are created by the addition
of trace elements during crystallization. Ferric Iron, Manganese,
Chromium or Vanadium impart color to the crystal.
Grossular Garnets can have a particular inclusion which is
an identifying characteristic. A treacle or swirly appearance
created by tiny included crystals, generally Diopside crystals,
is common to Grossular Garnets.
Major sources for Grossular Garnets are Canada, U.S., Mexico,
Africa, Australia and Brazil.
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Hackmanite
A variety of Sodalite, this extremely rare Gem is from Mt.
St. Hilarie, Ontario, Canada. Exposure to short wave ultraviolet
light causes Colorless or pale Yellow Hackmanite to fluoresce
bright Orange.
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Hambergite
This Gem is noted for having the lowest known density for a
Gem with such a high birefringence. Our faceted Hambergites
are transparent and Colorless with a hardness of 7.5. The stone
was named for Axel Hamberg, a Swedish mineralogist.
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Hauyne
From Germany, this intense, vivid Blue Gem is rarely found
in single mineral form. It is generally seen as one of the
components of Lapis Lazuli. Hauyne (pronounced Hi´ une) has
a hardness of 5.5 to 6.
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Herderite
This Brazilian Gem is found in hard granite and is difficult
to find in clean material. The stone has a hardness of 5-5.5
and is named for a German mining official, S.A.W. von Herder.
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Hessonite Garnet
Hessonite Garnet is part of the Grossular Garnet species. Known
in ancient times as the Lyncurium stone, Hessonite was found
then in India and Ceylon. In the 11th century, Hessonite was
ground and consumed as a cure for jaundice.
Hessonite Garnets are available in Yellow, Orange and Red/Orange.
The Red/Orange Hessonite is often referred to as "Cinnamon" stone
because it matches the color of oil of cinnamon produced in
Ceylon.
Modern sources for Hessonite are Canada, Mexico, U.S., Brazil
and Africa.
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Imperial Topaz
Imperial Topaz is found in only one location in the world,
Ouro Preto in the state of Minas Gerais in Brazil. The world's
entire supply of Imperial Topaz is mined in a 100 kilometer
(60 miles+) area around Ouro Preto. Most of it comes from two
mines, the Vermelhao Mine and the Capao Mine. Even though Brazil
has the richest and largest concentration of all Gem bearing
pegmatites, Gem experts still expect the Imperial Topaz sources
to be completely exhausted by the end of the century.
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Iolite
Iolite is a lovely violet Blue to Blue Gemstone which
is frequently substituted for the more expensive Blue Sapphire.
It is a transparent, generally eye clean stone with a hardness
of 7-7.5. Named for ios, Greek for violet, Iolite is often
referred to as the "water Sapphire".
Iolite, also known as Cordierite, is strongly pleochroic and
poses a challenge to cutters. Light is separated into three
distinct colors, so the Iolite must be cut with the proper
axis face up to produce top color. Viking sailors held thin
pieces of Iolite over their eyes on hazy or overcast days to
locate the exact position of the sun. The pleochroic nature
of the Iolite acted as a polarizer to eliminate the interference.
An ancient source for Iolite was Norway, but now it is mined
primarily in India, Tanzania and Zaire.
CHEMISTRY (Mg,Fe2) Al4Si5O18
CRYSTALLOGRAPHY Orthorhomic
REFRACTIVE INDEX 1.522 - 1.578
HARDNESS 7 - 7.5
SPECIFIC GRAVITY 2.53 - 2.78
CLEAVAGE Distinct 1 direction
HEAT SENSITIVE No
WEARABILITY* Very Good
SPECIAL CARE INSTRUCTIONS None
ENHANCEMENTS None
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Jadeite
Jadeite and Jade are used interchangeably by many people
who are not aware that there are actually two different
kinds of Jade. Nephrite Jade is the more common variety.
Both are cut as Cabochons for Jewelry and
used for carvings. Nephrite Jade typically has a waxy or
oily appearance.
Jadeite is a silicate of Sodium, Iron and Aluminum and
is a member of the pryoxene mineral group. The top quality
and most expensive Green Imperial Jadeite rarely is found
in the U.S. unless it is ordered by special request or
is an estate piece. Prices range in the thousands for a
small Cabochon. Other colors available in Jadeite are Lavender,
Pink, bluish Gray, Gray, White, rust Red, Orange, Yellow
and Black.
Jadeite has a hardness of 7 and is an exceptionally tough
stone due to the compactness of its small, granular crystals.
Consequently it is a difficult mineral to cut and carve,
more difficult than Gemstones which
rank higher on the Mohs hardness scale. Carvings have been
authenticated for the past 4,000 years. Each has a story
to reveal through the Asian motifs and the colors utilized
by the carvers. Many of the Jadeite boulders have colors
which tend to flow one into the other, creating an excellent
opportunity for the carver to incorporate these colors
into a unique design.
Jadeite and Nephrite Jade are both found in metamorphic
rocks. Jadeite is found in conjunction with other rocks
which are rich in Sodium. Burma, the primary source of
Jadeite, is the only consistent source of high quality
material. A rather primitive recovery system is used by
the workers. Fires are built on the rock face and then
quenched with water. The temperature shock cracks the rock
so the workers can split out the Jadeite chunks with hammers
and wedges, often with serious damage to the Jadeite. Guatemala
is another source of Jadeite, but no significant commercial
qualities have been available. It is primarily of interest
for its historical value.
Nephrite Jade is a silicate of Calcium Magnesium and is
a part of the tremolite actinolite series. Nephrite is
White in its pure state with other colors created by Iron
and mineral impurities. Colors available in Nephrite Jade
are pale to deep Green, Yellow, rust Red, Brown and Gray.
Like Jadeite, it is an extremely tough Gem. Nephrite Jade
has a hardness of 6 1/2. "Mutton Fat" Jade is
commonly seen in the market. It is a light grayish Green
to White color which resembles solidified lard when polished. "Buried" Jade
is ancient carved pieces that have become chemically altered
after centuries in the tomb due to the absorption of substances
from percolating water. It becomes relatively fragile and
changes to a Brown to blackish Brown color. Much Nephrite
Jade is recovered from stream beds in Western Canada, Alaska,
British Columbia, California and Wyoming.
Asians revere Jadeite above all other Gems. Every family
will own some Jadeite which is usually passed down in the
family from father to eldest son.
CHEMISTRY Jadeite, NaAlSi2O6. Nephrite, Ca2(Mg,Fe)5(Si4O11)2(OH)2
CRYSTALLOGRAPHY Monoclinic, though usually microscopic.
REFRACTIVE INDEX Jadeite 1.64 - 1.667. Nephrite, 1.600
- 1.641
HARDNESS Jadeite 6.5 - 7. Nephrite, 6 - 6.5
SPECIFIC GRAVITY Jadeite 3.25 - 3.36. Nephrite, 2.90
- 3.02
CLEAVAGE None
HEAT SENSITIVE No
WEARABILITY* Excellent
SPECIAL CARE INSTRUCTIONS None
ENHANCEMENTS Dying, occasional. Wax impregnation, occasional.
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Jasper
Jasper is a variety of Cryptocrystalline Quartz which is
available in several colors, primarily due to Iron. Leopard
Skin Jasper is named for its spotted pattern. This Jasper
has light Brown to Tan background with spots in dark Green,
dark Brown, deep Orange or Yellow. Braciated Jasper has
the rust Red background with veining usually in Tan and
Black. Picture Jasper denotes the scenes that can be recognized
in its patterns. It has a Tan background with swirls of
dark Brown, Black and White.
CHEMISTRY SiO2
CRYSTALLOGRAPHY Hexagonal, microcrystaline.
REFRACTIVE INDEX 1.544 - 1.553
HARDNESS 7
SPECIFIC GRAVITY 2.651
CLEAVAGE None
HEAT SENSITIVE No
WEARABILITY* Excellent
SPECIAL CARE INSTRUCTIONS None
ENHANCEMENTS May be dyed.
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Kanchana-buri Blue Sapphire
Kanchanaburi is a region in Thailand that produces a beautiful
Blue Sapphire in
various qualities.
Kanchanaburi Sapphires are
mined in a province of Thailand bearing the same name. It is
almost 100 miles west of Bangkok. Most of the mines are located
near the small village of Bo Phloi, which means "gem pit" in
Thai. The Bridge over the River Kwai is nearby. In 1992 there
were literally hundreds of "mines" operating in this
area, most producing very little rough. In recent years the
largest and most productive was transformed into a golf course
and resort as the land was mined! Now there is NO steady production
of Kanchanaburi Blue Sapphires.
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Kashmir sapphires –
blue velvet
The famous sapphires of
Kashmir are mined from a remote region high in the Great Himalayan
mountains of northwestern India. Lying at an elevation of approximately
4,500 m, they are located in the small Kudi ('rock') Valley,
near the hamlet of Sumjam (Soomjam), in the Padar (Paddar)
region of Kashmir. The district of Zanskar, which has been
incorrectly listed as the source of the sapphires, lies just
to the north (Ball, 1885b; Steve Karpa, pers. comm., 1990).
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Kashmir sapphires range
from near colorless through a deep blue, with the occasional
pink to purple stone found. The large fine gems of
years gone by were generally cut from the blue areas of much
larger crystals. Those specimens that possess smooth faces
contain this blue layer intact. However, many pieces feature
heavily corroded surfaces and thus the blue layer is only partially
present, if at all. The following description of Kashmir sapphire by
Jaipur gem trader, Rajroop Tank tallies well with the author's
experience:KASHMIR:--The Sapphires of
Kashmir form an exclusive class of their own. In the Jewel
trade it is customary to attach the appellation 'Kashmir' to
any fine Sapphire regardless
of its geographical origin. This is an indication of the outstanding
qualities of Kashmir Sapphires. The colour of these Sapphires resembles
the beautiful hue of the peacock's neck. Even a small concentration
of that fine colour illuminates the entire structure of the
Gem.
It may, however, be noted that the product of the Kashmir mines
suffers more from flaws and blemishes than that of many other
mines. The Gems of
Kashmir mines often have window, hole, or cavity in their texture,
and they also suffer at times from ambiguity of colours. It
requires special skill to cut the Jewels as the crystals are
covered with a hard crust of earth and it is difficult to know
beforehand the internal structure. If a specimen is free from
cavity or window and does not exhibit ambiguity of colour it
can be cut into an excellent Gem. The produce of the old mine
in Kashmir did not suffer from so many blemishes, but the Sapphires of
that mine are no longer available.... Kashmir Sapphires generally
remain thick after cutting. Stars are not found in them.
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Kornerupine
This unusual mineral was first discovered in Greenland, but
most are now found in Sri Lanka, Burma and Kenya. Kornerupine
is considered to be a rare Gem in both faceted stones and Cabochons.
Kornerupine was named for the Danish geologist, A. N. Kornerup.
Its crystals grow in the orthorhombic system, and it has a
hardness of 6 to 7.
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Kunzite
Kunzite is probably the best known member of the Spodumene
mineral family and has a hardness of 6.5 to 7. This lavender
Pink Gem was named for George Kunz, the noted Gemologist for
Tiffany & Company. Kunzite is frequently encountered in
very large sizes and in deep cut Gems as
a way of maximizing the color. Smaller stones, those under
10 Carats, will usually have lighter color than larger ones.
Our transparent, faceted stones are from Brazil and Afghanistan
and range from light to medium dark lavender Pink. Price per
carat indicates the depth of color.
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Kyanite
Kyanite is a rare Gem which is noted for its color zones. This
stone is typically found in shades of greenish Blue with darker
zones of the same color running parallel to the long axis.
Our Kyanite is transparent and faceted with some visible inclusions,
usually fibrous in nature. Kyanite's hardness is 4 to 7.5 in
the same crystal depending upon axial direction. This Gem is
very difficult to cut because of its one perfect direction
of cleavage and extreme variability in hardness.
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Labradorite
Labradorite is a member of the Feldspar family and has a hardness
of 6 to 6.5. Most of the Feldspars are opaque and are cut as
Cabochons. Our transparent, Yellow Labradorite is from Canada.
CHEMISTRY Variable composition of NaAlSi3O8 and CaAl2Si2O8
CRYSTALLOGRAPHY Monoclinic
REFRACTIVE INDEX 1.560 - 1.572
HARDNESS 6 - 6.5
SPECIFIC GRAVITY 2.69 - 2.72
CLEAVAGE Perfect two directions.
HEAT SENSITIVE No
WEARABILITY* Poor
SPECIAL CARE INSTRUCTIONS Avoid rough handling
ENHANCEMENTS None
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Lapis Lazuli
Lapis Lazuli is known as the Egyptian royal Blue stone of Heaven.
Lapis was one of the first materials to be mined and worked
as a Gemstone. The Pharaohs of Egypt sent runners from Egypt
to Afghanistan to obtain Lapis for the court Gem cutters. Today
Afghanistan is still the main source for the finest Lapis.
CHEMISTRY (Na,Ca)8(Al,Si)12O24(S,SO4)
CRYSTALLOGRAPHY Isometric
REFRACTIVE INDEX ~ 1.50
HARDNESS 5 - 6 depending on impurities.
SPECIFIC GRAVITY Pure, 2.38 - 2.45. Gem grade usually 2.7
- 2.9 but can be higher if much pyrite is present.
CLEAVAGE Imperfect.
HEAT SENSITIVE ?
WEARABILITY* Good
SPECIAL CARE INSTRUCTIONS Avoid contact with chemicals
ENHANCEMENTS Dying, common
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Malachite
Malachite is a Green banded mineral which gets its name from
the Greek word mallow, an herb plant, in reference to the color.
The finest material is found in Zaire, the source for our Gemstones.
Malachite has a hardness of 3.5 to 4.5.
The rich, patterned Green coloration of Malachite is unique
among Gemstones. Cabochons, beads, boxes and in Russia even
place settings, including dinner plates and goblets, have been
carved from Malachite.
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Malaya Garnet
Malaya Garnets are a combination of two Garnet species: Pyrope
and Spessartite. This Orange Garnet has an unusual history.
In the late 1970's, East African miners included this Orange
and reddish Orange stone in parcels of Rhodolite Garnet being
offered to Japanese dealers. The "off" colors, summarily
rejected for their obviously different color, were contemptuously
called Malaya by the miners. This Swahili word means outcast
or prostitute. Fortunately German and American dealers saw
the beauty of this "outcast" Gem and began marketing
Malaya Garnet in 1979.
Top color Malaya Garnets are pure Orange or Red/Orange, sometimes
with a touch of Peach. These vibrant stones are beautiful mounted
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Mali Garnet
The beautiful Mali Garnet is the latest discovery in the Garnet
family. From Mali, Africa, these attractive Garnets are a rare
mixture of Andradite and Spessartite and only came into the
market in late 1994. Mali Garnets are much rarer than Tsavorite
Garnets. All of our stones are a bright, uniform light yellowish
Green.
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Mandarin Garnet
This "Sunkist" Orange Garnet is a newcomer to the
Gem Markets. Discovered in 1992 in Namibia near the north border
with Angola, Mandarin Garnet is mined in wasteland conditions.
Temperatures have been known to reach 140°F in a desert area
populated by Angolan soldiers who have fled their homeland.
Mandarin Garnet is part of the Spessartite Garnet species and
has a hardness of 6-6.5. Its uniform, vivid color of pure Orange
sets it apart from other Orange stones. Garnets take a good
polish, so this is a beautiful Gem for mounting.
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Manganotantalite
This rare collector's gem has a high dispersion, so it is quite
bright. Our facet gem is deep, rich Red with slight visible
inclusions. Manganotantalite has a hardness of 5.5 to 6.5.
It was named for its chemical composition, manganiferous tantalite.
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Maw-Sit-Sit
Maw-Sit-Sit is a stunning Green Burmese Gemstone that
is found only in a town of the same name in Burma. Maw-Sit-Sit
is a very rare Green Gem that is hard enough to be used in
unique jewelry It
is opaque to translucent, electric Green with swirling veins
of darker Green or Black and sometimes with White spots. It
is found where Jadeite is formed by the same high pressure
required to form Jadeite and is often confused with various
forms of Jade.
Maw-Sit-Sit is not Jade but contains a composition of Chrome
Jadeite, Ureyite and Natrolite. The Gem was first identified
by world renown Swiss Gemologist Eduard Gubelin in 1963. Rough
stones are usually found in sizes from 4 Carats to 40 Carats
and has a hardness of 6.0.
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Moissanite
Moissanite is not yet a familiar name to many buyers, but in
mid-1998 it began to make a huge splash in the gem world as
the latest and greatest diamond simulant.
This synthetic silicon carbide crystal was discovered by a
materials scientist at North Carolina State University and
is being developed by C3 and Cree Research. Its natural counterpart
has been found only in meteorites and is deep green, but the
synthetic moissanite is near colorless and will probably fool
quite a few jewelers and jewelry buyers
before it becomes better known. Its high refractive index and
extreme hardness (second only to diamond) make it an effective diamond simulant,
and the popular diamond probes
that test thermal conductivity fail to distinguish it from
diamond. C3 is also marketing a new detector that can distinguish
between moissanite and diamond, but it will take some time
before many jewelers have it.
One way to identify it is by its double refraction -- look
through the stone from several different angles and you should
see double images of facet lines or objects viewed through
the stone. If you look directly through the table, you're not
likely to see the doubling, though, since it's oriented on
the optic axis. Keep your eyes out for this one!
Manmade garnets such as YAG (yttrium aluminum garnet) and GGG
(gallium gadolinium garnet) and other materials such as synthetic
rutile and strontium titanate preceded cubic zirconia as diamond simulants
but were never very convincing in that role. With the advent
of CZ, their role in the market has declined considerably.
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Montebrasite
This Brazilian stone is a transparent Gem with a hardness of
5.5-6. Its name is derived from the French locality where it
was first discovered. It is frequently misidentified as Amblygonite,
but Montebrasite has a positive optic sign while Amblygonite's
sign is negative. Montebrasite is offered in faceted bright,
medium mint Green and faceted bright light Yellow.
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Morganite
THE PINK EMERALD!
Several years ago I told you about a promotion on MORGANITE
(THE PINK EMERALD) and made you some fantastic offers from
our stock. At that time we just about sold out, and those who
bought MORGANITE then have made money on every stone we sold!
The promoter of the PINK EMERALD even
reported on his trips to Europe to buy from the Gem centers
there and was paying MORE for some Morganites than we charged
our clients at that time! Amazing, but true. There has been
some action on TV with MORGANITE in the small sizes. The stones
I have seen have a pale washed out color.
This is glitter and glitz! These stones are plentiful and very
CHEAP as they have no size nor color for a collector of Gemstones.
Fortunately the public is aware of MORGANITE, but it is very
difficult for them to find a "choice" stone like
ours. The promotion of several years ago died out due to lack
of supplies. Perhaps the originator thought there was an endless
supply and only later discovered how rare this Gem truly is
in the larger sizes with good color. I can tell you for a fact
that there have been NO stocks coming into the market since
that time and the price has consistently gone up. The ONLY
stones we have are those which were in our stock at that time
or ones we bought back from clients. I know of no other stocks
in the world markets! MORGANITE is one of the continued "BEST
BUYS" for 1996. You should act on these offers at once.
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Morro Redondo Tourmaline
This is a report on the largest occurrence of Tourmaline
in the history of Brazil gem mining; the Morro Redound Tourmaline
of the State of Minas Gerias Brazil. The material was first
discovered in 1992 near the village of Morro Redondo, in
the northeast of Minas Gerias.
The first pocket was found halfway up the side of a mountain.
It contained a modest amount of Gem Blue Tourmaline. Then
on the following rise, they found 3 more pockets. One of
all Black Tourmaline mostly terminated ends with a layer
like surface terminations running parallel to the
"C" axis. Creating a "Pueblo" effect.
The next contained Morganite crystals up to 2 kilo in size.
Very clean Peach to Bi-color material. It was at this point
that a very unique treating process was discovered that gave
inspiration to the later developments in Tourmaline treatments.
This Peach type of material was first heated to White, then
subjected to 450 megarads Colbolt irradiation. It turned
to various shades of Green. Then reheated to a uniform pale
Pink.
The final Tourmaline pocket was 10-15 meters square. They
began by sinking holes to a depth of 3 meters. The Tourmaline
discovered was a Brownish to Pink "A" axis, often
found complete in Bi-color Blue/Green and Brown/Pink; the "C" axis
being a Red to Pink/Peach. The bulk of the material was extraordinarily
clean and well formed. With the exception of the Blue/Green
side of the Bi-color pieces. This end is almost always lightly
included. Where the two colors join often is observed a light
to heavy silk. Many having a Gem Cat's eye effect. This pocket
(they named it Elba) produced a record 47 tons of Tourmaline
total from February 1992 to March 1996. The first 8 tons
of production was seized by local authorities and auctioned
for Taxes to a Govenador Valadares Firm of Miranda for $
60/kg. At mid production they tunneled in from the side and
the entire top above collapsed. All along the sides and bottom
of the pocket were matrix specimens of Tourmaline, Albite.
Lepidolite, and Quartz.
Although sparsely reported in the United States, this Tourmaline
dominated the Gemstone industry
in Brazil for almost 4 years. Sales of ton lots of rejection
(heavily included) material were common. There were over
400 miners at the site at peak. The squares and Gem trading
streets of Arasuai, Teflo Otoni and Gov. Valadares were smothered
with small miners selling their weekly productions. Mine
Runs went from a low of $ 60 initially to $ 150/kg in the
first week of July 1996. Clean needles under 1 gram in size
went from as little as $ 200 per kilo to $ 4/gm (July, 1996).
Larger sizes (up to 100 gram) began at $ 10-20/gm and now
are scarce, and almost seller's prices. Material of all grades,
although rising daily in price, will continue on the market
until sometime in August 1996, attesting to the massive task
of sorting out the tonnage produced.
This Tourmaline is preferably cut down the "C" axis,
producing Strawberry-Red and Peach-Pink Stones. Commercially
the finished stones are first heated to 600C to turn to white,
then heated further to 680-700C to gain a Pinkies hue. Then
the stones are given 80-100 megarads of Colbolt irradiation
to return a fairly uniform "hot" red color. Adjustments
by heating are made to those that treat too dark on the final
stage.
So, good-bye Morro Redondo. This Gemstone rough
production now in it's final stages is only this year reaching
the U.S. Market. And throughout it's introduction to present
the cut stone prices appear to be stable at around $ 35-50/cts.
for Parcels of calibrated goods in New York. Odd colors and
rejections trading as low as $ 3/cts. And certainly for several
years to come this discovery will be the Pink Tourmaline
of choice due to it's astonishing production and now widespread
availability.
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Mozambique Garnet
This bright Red Garnet with Orange flashes is found only in
one mine in Mozambique in Southeastern Africa. No rough material
has been produced for quite some time. Since the Socialist
takeover, the mine has flooded and collapsed. Political instability
continues to devastate that country.
Mozambique Garnet is part of the Almandite Garnet species.
It is a bright Gem with no eye visible inclusions.
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Opal
CHEMISTRY SiO2 . nH2O. Water usually 6 to 10% in precious
opal, can be as high as 21%.
CRYSTALLOGRAPHY Amorphous.
REFRACTIVE INDEX 1.44 - 1.47
HARDNESS 5.5 - 6.5
SPECIFIC GRAVITY 1.99 - 2.25
CLEAVAGE None.
HEAT SENSITIVE Very
WEARABILITY* Poor
SPECIAL CARE INSTRUCTIONS Very heat senstive, clean with
warm or room temperature soap and water. Avoid wearing gem
where it will get rough treatment.
ENHANCEMENTS Impregnated with oil, wax, or plastic. Occasional.
Smoked, to create black opal. Occassional. Treated with dye
or chemicals to make light opal black. Occasional.
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Orthoclase Feldspar
These intense Yellow Gem has been expertly faceted in the Portuguese
pattern of 144 facets. Beautiful Gems! Orthoclase is a silicate
of Aluminum and Potassium.
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Padparadscha Sapphire
Padparadscha is the Sinhalese word meaning lotus blossom. Padparadscha
is Corundum in the Orange color range, usually Pink/Orange
to Red/Orange. Padparadscha Sapphire is
rarer than fine Ruby.
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Pearls
Pearls have a unique vocabulary used to adequately describe
them. Here are the terms used most often:
Origin. Possibilities include natural (rare and extremely valuable),
cultured (most, still quite valuable), or simulated (fake;
generally very inexpensive unless very convincing).
Body Color. This is the basic color of the pearl (as opposed
to any overtone color). Possibilities range from white, to
pink rose, to creams, to blues, grays, silvers, yellows, golds,
and blacks.
Luster. This refers to the brightness and sharpness of reflections
seen on the pearl. It ranges from dull to very bright or very
high.
Nacre thickness. This is the thickness of the outer layer of
the pearl. It runs from very thin (less than .25mm) to very
thick (.5mm or more). The remainder is the interior, implanted
bead. Natural pearls are nearly 100% nacre; simulants have
no true nacre.
Shape. This indicates the pearls' "sphericity," or
how perfectly round they are. The grades run from "All
Round" (all pearls are perfectly round and drilled on-center)
to "Baroque" (distinctly asymmetrical).
Spotting. This is sometimes called blemishes. The grades run
from flawless (no blemishes at all) to heavily spotted (nearly
all are noticeably blemished).
Make. This refers to how well matched a strand or set of pearls
are, and runs from Excellent (all are uniform in appearance
and size) to Poor (more than 1/3 show noticeable variation
from the "norm").
CHEMISTRY CaCO3 (aragonite, the outer layer) about 82 -
86%, conchiolin 10 - 14%, water 2%.
CRYSTALLOGRAPHY Aragonite is orthorhombic, with crystals
radially oriented.
REFRACTIVE INDEX 1.53 - 1.69
HARDNESS 2.5 - 4.5
SPECIFIC GRAVITY 2.6 - 2.78.
CLEAVAGE None
HEAT SENSITIVE Yes
WEARABILITY* Good
SPECIAL CARE INSTRUCTIONS Avoid heat and all chemicals,
including perfume and other cosmetics.
ENHANCEMENTS Dying, common
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Peridot
Peridot, the birthstone of August, is a member of the Olivine
mineral group. It is a Mangnesium Iron Silicate. The amount
of Iron determines the color saturation. Peridot ranges in
color from yellowish Green to deep olive Green and has a hardness
of 6.5-7.
Peridot's name is derived from the Greek peridona, meaning
to provide plentifully. The ancients referred to it as the "gem
of the sun" and believed that it could banish evil spirits
and break enchantments when it was worn in a Gold setting.
Peridot is considered a stone of hope. It is supposed to strengthen
the sight, heart and respiratory system and aid against depression.
Peridot has great historical and religious significance. Peridot
from Egypt found its way either by loot or trade to the cathedral
treasures of Europe during the Crusades. At that time, these
Green Gems were
called Emeralds. The most notable are in the treasury of the
Three Magi in the great cathedral at Cologne, West Germany.
The U.S. has become the major source for Peridot since the
world's largest known deposit is on the San Carlos Apache reservation
80 miles west of Phoenix, Arizona. The rough is dug by Native
Americans who sell to nearby dealers. The faceted Arizona Peridot
is bright, yellowish Green with minimal inclusions.
The Burmese Peridot is a rich olive Green and one was readily
available in large Gem quality stones. Sources for these fine
stones are quite limited now, and premium prices can be demanded
for fine, Gem quality Burmese Peridots. We are fortunate to
have several large Burma Peridots at "old" prices.
CHEMISTRY Mg2SiO4-Fe2SiO4
CRYSTALLOGRAPHY Orthorhombic
REFRACTIVE INDEX 1.635 - 1.673
HARDNESS 7
SPECIFIC GRAVITY 3.3 - 3.4
CLEAVAGE Imperfect
HEAT SENSITIVE No
WEARABILITY* Very Good
SPECIAL CARE INSTRUCTIONS None
ENHANCEMENTS None
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Petalite
These bright, transparent Colorless Gems are
found in Brazil. Several years ago they were being promoted
by some of the scam Gemstone investment
groups, and the price was highly inflated. Petalite has a hardness
of 6-6.5
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Phenakite
Phenakite has a hardness of 7.5-8 and is suited for jewelry wear.
Our Colorless stones are transparent with nice cuts. Phenakite
is named for the Greek word meaning "deceiver" because
it was often mistaken for Quartz.
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Pyrope Garnet
In ancient times, Garnets were considered special and were
known as the "fiery Gemstones." In fact, Pyrope in
Greek means "I see fire." Our stones are from the
Navajo Reservation in Apache County, Arizona, and are known
as Ant Hill Garnets. The ants will bring the Pyrope crystals
to the surface as they build their large mounds, a visible
indication to the miners that Pyrope crystals lie underneath.
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Quartz (Crystalline)
Crystalline quartz is quartz that occurs in distinct crystals.
It occurs in a number of familiar varieties distinguished by
color.
Amethyst is purple quartz and is one of the most popular gemstones.
It varies from pale lavender ("Rose-de-France" amethyst)
to deep purple with red highlights ("Siberian" amethyst).
Amethyst is generally abundant and quite inexpensive (pennies
to a few dollars per carat), although fine, large Siberian
amethyst is rather scarce and may command prices of several
tens of dollars per carat. When exposed to strong sunlight
for extended periods, amethyst may fade in color. Recently,
gem markets have been flooded with inexpensive synthetic amethyst.
Although such synthetics can usually be identified by testing
for twinning, routine testing is not cost-effective, and some
new synthetics do not show the twinning effect.
Citrine is yellow to brown quartz. It varies from pale yellow
to rich golden yellow to dark orange. Although citrine may
occur naturally, much is produced by heating amethyst under
controlled conditions (overheating drives off all color, leaving
colorless rock crystal). Darker colors are more highly prized,
including medium golden orange ("Rio Grande" citrine)
and dark sherry-colored ("Madeira" citrine).
Ametrine is a combination of amethyst and citrine within a
single crystal and was discovered only a few years ago in Bolivia.
Such bicolored stones are fairly unusual and can be very striking
in appearance, but prices remain rather low. For a brief period,
these stones were erroneously thought to be manmade or treated
to produce the bicolor effect, but it is now known to occur
naturally.
Vermarine, also known as Prasiolite or "Greened" Amethyst
is a light to medium green quartz produced by careful heating
of amethyst from one Brazilian location. Although inexpensive,
it is seldom seen and remains something of a collector's item.
Rock Crystal is clear colorless quartz. Its value tends to
be very low, except for large flawless pieces, which are rare.
One of the finest known pieces is the 12.75 inch diameter,
107 pound flawless sphere ("crystal ball") in the
collection of the Smithsonian Institution.
Rose Quartz is pink quartz. It is usually translucent to semitransparent.
Strong rose-red, transparent material is rare. Like amethyst,
it may fade on prolonged exposure to strong sunlight.
Smoky Quartz is tan or brown quartz. Very dark reddish brown
smoky quartz is known as cairngorm (from the Cairngorm Mountains
in Scotland), and black or blackish brown material is known
as morion.
Cryptocrystalline Quartz
Cryptocrystalline quartz is quartz in which the crystals are
microscopic in size and thus is always opaque or translucent.
It occurs in a huge array of colors and patterns and, like
crystalline quartz, occurs in myriad locations.
Agate is a chalcedony that displays an incredible variety of
color patterns -- generally curved bands of regular or irregular
formation. It occurs in myriad locations, and some forms are
rare and relatively expensive.
Aventurine is a more or less colorless chalcedony that contains
uniformly dispersed flakes of greenish mica, thus giving the
stone a characteristic speckled green appearance known as aventurescence.
Bloodstone, also known as heliotrope, is a dark green chalcedony
or jasper with flecks of red.
Carnelian or cornelian is a reddish brown chalcedony. In ancient
Rome, it was often used in cameos and intaglios.
Chalcedony is a translucent or semitranslucent cryptocrystalline
quartz, which may be patterned (agate) or uniform in color
(blue, green, pink, black, white, etc.).
Chrysocolla quartz is chalcedony mixed with varying amounts
of chrysocolla. The chrysocolla provides the robin's egg blue
coloration, and the quartz provides sufficient hardness for
use in jewelry The
durability varies with the corresponding proportions of the
two components.
Chrysoprase is a light to medium, slightly yellowish green
chalcedony. Australia provides many of the finest examples.
Fire Agate is chalcedony that contains many layers of tiny
inclusions of limonite or goethite, which produce a distinctive
firelike iridescence when properly cut to leave only thin protective
layers of chalcedony over the inclusions. Many of the finest
specimens have been found in Arizona.
Jasper, in contrast to chalcedony, is an opaque and more coarsely
grained cryptocrystalline quartz. Like chalcedony, it may be
patterned or uniform in color.
Picture jasper, or scenic jasper, may display quite realistic
depictions of natural scenes, animals, or other objects, and
can command respectable prices due to such unusual pictures.
Onyx is something of a catchall term that usually refers to
dyed black chalcedony ("black onyx"), but it is also
used to describe other colors of dyed chalcedony. More strictly
speaking, onyx agate is banded agate displaying straight and
parallel bands of alternating colors, which has historically
been used to produce cameos. (See sardonyx.) True onyx, however,
is a form of calcite, usually used in architecture and ornamental
pieces.
Petrified Dinosaur Bone or "dinny bone" is the product
of millenia-old fossilized bone (from dinosaurs!) in which
the cellular contents have been replaced by quartz, leaving
the cellular bone structure intact. The deserts of the American
southwest (notably Utah) produce many fine specimens.
Petrified Wood, like petrified bone, retains the cellular structure
of the original wood, but the cellular contents have been replaced
by quartz.
Prase is a light yellow-gray-green chalcedony.
Sard is a darkish brown chalcedony similar to carnelian but
of less intense color.
Sardonyx is an agate with alternating straight, parallel bands
of reddish brown and, usually, white.
Tigereye is a yellowish brown cryptocrystalline quartz in which
quartz has replaced crocidolite, a fibrous, asbestos-like mineral.
The parallel fibrous structure produces a characteristic chatoyance
(silky sheen), or even a cat's-eye effect. Gray, green, and
blue (hawk's-eye) tigereye are also used as gemstones; they
are usually the result of chemical or heat treatment. Tigereye
is often used for cameos and intaglios.
Turritella is an agglomeration of fossilized turritella snail
shells replaced by silica. Wyoming is the principal source.
CHEMISTRY SiO2
CRYSTALLOGRAPHY Hexagonal
REFRACTIVE INDEX 1.544 - 1.553
HARDNESS 7
SPECIFIC GRAVITY 2.651
CLEAVAGE None
HEAT SENSITIVE No
WEARABILITY* Very Good
SPECIAL CARE INSTRUCTIONS None
ENHANCEMENTS Irridation, dying, heat treatment for
colored varieties only. Occasional.
*Wearability is graded as Excellent, Very Good, Good, Poor,
and Forget It!
For more details see the article on "Hardness and Wearability."
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Spinel
Spinels are genuine Gemstones with
a long history. The availability of Red, Pink, Blue, Purple
and Orange Spinels and all of their accompanying shades has
created confusion between natural Spinel and other Gems for
those unfamiliar with this natural stone.
Spinel is a mineral group composed of Magnesium Aluminates.
The addition of Chromium produces Pink or Red Spinels. Iron
or Titanium additions produce Lavender or Blue Spinels. The
octahedron Spinel crystals are typically found in metamorphic
pegamites or as pebbles in steam beds. Spinel has a hardness
of 7.5 to 8 and takes a brilliant polish, so it is an excellent
choice for jewelry Generally
Spinel crystals are quite clear and clean of flaws.
Spinel received its name from either the Greek spina meaning "little
thorn" or from the Greek spinther meaning "spark" in
allusion to its color. Curative powers from hemmoraging and
inflammatory diseases were credited to Spinel. It was reputed
to have a calming effect and the ability to remove anger and
discord.
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Raspberry Spinel
This rich Pink Spinel with intense Raspberry flashes was discovered
in the early 1980's and entered the markets in 1983. The color
was so exciting that the supplies would not keep up with the
demands from the public! Our inventory remains low.
This vibrant Spinel was found in the Pamir Mountains of Central
Asia on the borders of Pakistan, Afghanistan, China and Russia.
A small deposit was located at the 10,000 foot level. Accessibility
is a problem, but the weather creates tremendous difficulties
for the miners. The harsh, long winters bring temperatures
below zero while the temperatures in the short, incredibly
hot summers can read 115°! The mining season is restricted
to a few months each year, so production will always be a problem.
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Rhodochrosite
Rhodochrosite is one of the most exciting of America's Gemstones.
This vibrant pinkish Red to rose Red Gemstone is
a secondary mineral composed of Manganese Carbonate found in
Colorado at the Sweet Home Mine. This mine is at an elevation
of 11,600 feet in the central Colorado Rockies. It's a 2 hour
drive southwest of Denver, near Alma. Here the mining season
is limited by snow to 5 months.
The Sweet Home Mine began operation in 1872 and holds one of
the earliest mine patents, U.S. #106. The mine was originally
opened for Silver, but production has been sporadic. 1966 marks
the last year that Silver was mined at the Sweet Home Mine.
Rhodochrosite was first considered a by-product at the Sweet
Home Mine, and most of the quality was obscure and, as a mineral,
was considered worthless. Occasionally, a Gem quality crystal
was discovered, but the large, transparent crystals were rare.
Since Rhodochrosite occurs in veins, often in conjunction with
Pyrite, Chalcopyrite, Galena, Sphalerite or Tetrahedrite, miners
began searching for Gem Rhodochrosite crystals near finds of
those minerals. The best crystals are created when hydrothermal
solutions flow into faults or fissure voids or pockets with
enough space for the crystals to develop.
In 1991 Bryan and Kathryn Lees, both engineering graduates
of the Colorado School of Mines, headed a group to mine Gem
Rhodochrosite crystals at the Sweet Home Mine. More than $500,000
was spent rebuilding the portal, constructing a drainage system
inside the mine, removing the mine's old rail system, installing
a ventilation system and slabbing the walls for a diesel load-haul-dump
unit. With the hiring of a mine manger and 2 miners, the Lees
began operation.
But nothing is easy in mining, especially when the mineral
being extracted is a soft one found in a hard bedrock. It is
important to remove the entire Rhodochrosite crystal intact
because the sale of undamaged crystal specimens is a large
part of this mine's income.
The Sweet Home Mine lies between two major geological faults.
The Lees had a geologist map out the entire mine in an attempt
to locate its faults and fissures, likely spots for Rhodochrosite
crystals. From past discoveries, it was determined that Rhodochrosite
is usually found with Tetrahedrite at intersections of mineralized
structures. The miners attempted to estimate the location of
these structures with GPR, ground penetrating radar, which
shoots bursts of high frequency electromagnetic energy into
the solid rock or earth. The response goes to a receiver and
records reflections of that energy from dielectric discontinuities.
These discontinuities, or breaks in the conductivity, reveal
the voids and the contacts between nonmineralized and mineralized
rock. The GPR surveys and the geologist's maps of probable
voids assisted the miners in localizing mining sites. But typical
blasting and jack hammers are not feasible if the crystals
are to survive the mining process.
Once a void is located, the crew inserts a medical fiber optic
endoscope through the drill hole to reveal any Rhodochrosite
crystals. Only 10% of the pockets reveal crystals of any value.
Near suspected voids, a series of drill holes are placed and
low energy detonators are used. A hydraulic splitter is used
to break the hard rock connecting the line of drill holes.
This is a time consuming process, but large sections of void
walls are freed with the crystals intact.
The finest crystal recovered from the mine is the "Alma
King," a 2 foot tall specimen with 2 perfect rhombohedrons
of Rhodochrosite on a matrix of White needle Quartz, Blue Fluorite,
Black Sphalerite and Tetrahedrite. Extraction took three weeks!
The "Alma King" was covered in natural Carbonate
Silicate, mud and dust from the drilling. Kathryn Lees developed
a cleaning process which would adequately remove the layers
but would not damage the Rhodochrosite or its adjacent crystals.
The Lees estimate that it required 3 months to clean and restore
the "King," which is described as the finest mineral
specimen ever mined in North America.
Mineral collectors have always admired the Colorado Rhodochrosite
for its lively color and its perfect rhombohedron shape. The
mineral is a soft one with a hardness of 3.5-4, so jewelry use
is limited to earrings, brooches or pendants. The faceted Rhodochrosites
are rare, since the Gem crystals which are mined intact are
sold as specimens. Only 5%of the yearly production is faceted,
and less than 5% of that production is of Gem quality. To date,
less than 400 stones have been faceted from the Sweet Home
Mine rough Rhodochrosite.
Most of us fail to consider the conditions of the mining process
and the expensive preparation that is necessary to even arrive
at that stage. We see the glittering Rhodochrosite, admire
its beauty and appreciate this gift of nature, but it does
not register that this Gem was 30,000,000 years in the making.
Most Gem crystals retrieved from the earth are not attractive
and would not receive a second glance from the layman. Time
and expertise is required before they are ready for the market,
either as specimens or as cut Gems. For those of us who love
Gemstones, we learn and grow in our appreciation for all Gemstones and
judge each on its own merits. The Colorado Sweet Home Rhodochrosite
Mine produces a beautiful Gemstone which
is valuable for its intrinsic beauty and rarity.
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Rhodolite Garnet
Rhodolite is the name used to describe the lovely pinkish,
purplish or lavender Red Garnets which are a mixture of Almandite
and Pyrope. This name was first used in the late 1800's to
describe the new rhododendron shade of Garnets discovered in
North Carolina.
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Rose Quartz
Rose Quartz is available in transparent to translucent light
to medium Pink. Titanium oxide is the impurity which creates
the Pink hue. Much of the faceting material comes from Brazil.
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Rubellite
Red Tourmaline is called Rubellite because the deepest shades
appear to be Ruby-like. Eye clean Rubellite is one of the most
expensive of the Tourmalines because generally it is an included
stone. Clean Rubellite is very rare.
Rubellite's intense color makes it a beautiful Gem for mounting.
Colors range in Rubellite from Fuchsia to maroon Red to Red.
The price of Rubellite goes up dramatically as the size increases
or the Red deepens in intensity.
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The name Ruby is
derived from the Latin word for red, rubrum. Its color varies
from purplish and bluish red to orange-red in medium to dark
hues. Sister to Sapphire , Ruby is
known in the mineral world as corundum, which is a crystal
structure composed of aluminum oxide. Only red corundum is Ruby ,
all other corundum colors are classified as Sapphire .
Ruby is
considered the most valuable variety of the corundum.
In fact, large Ruby Rubies have
consistently brought higher prices per carat
at auctions than the most flawless, colorless Diamond Diamonds!
This is primarily due to the rarity of gem-quality
rough Ruby .
The most famous source for natural gem-quality ruby is
Myanmar (Burma). Good stones have also come from Thailand,
Sri Lanka, and most recently, Vietnam. However, Myanmar remains
the largest and best source for Ruby Rubies of
top-quality, free of inclusions and a dark-pink red color that
holds its glow in all lighting conditions. Rubies are
also mined in Africa, Afghanistan, and Central Asia, but these
mines have yet to yield a significant source of good rough
stones. The center of the Ruby trade
is in Thailand, in Chantaburi as well as near the Myanmar border,
as close as one can get to the mines without being under the
totalitarian Myanmar military government. Many of the best Ruby cutting
and polishing traditions are in the Thailand, and much of the
international trade of finished stones takes place in Bangkok.
On the Mohs scale of hardness, Ruby ranks
9, sharing status with Sapphire as
the highest in the gem world after Diamond Diamond.
It is considered very durable, a great choice for rings and
bracelets that are prone to knocks. Although Ruby is
not as brilliant as Diamond Diamond,
it has striking luster. Like sapphire, Ruby may
be found in a translucent variety that may display a six-rayed
star effect when cut into a cabochon (dome) shape. This type
is known as star Ruby ,
of which there are numerous synthetics on the market.
Perfect natural gems in
color and appearance are very rare and expensive. Controlled
heating is commonly used in the trade to produce, intensify
or lighten color and/or improve clarity. This allows the trade
to bring more, better quality gems to
the market. Heat enhancement is permanent and stable. You can
clean treated or untreated Ruby Rubies the
same with soapy water or a gentle commercial solvent and a
brush. Mechanical cleaners are also safe, except with heavily
included gems.
Some Ruby Rubies have
fissures that break the surface and are filled with a glass-like
byproduct from the heating process. Surface cavities in rubies are
also intentionally filled with such material as glass, solidified
borax or similar colorless substances to improve its durability
and appearance. These enhancements may wear over time if treated
harshly or exposed to strong abrasives and solvents, as well
as heat. The filler material used is fragile and may fall out,
break or abrade. It is important to buy fine Ruby from
a reputable retailer who will provide, in writing, all pertinent
information regarding the gem including enhancements and special
care notes.
Ruby ,
July's birthstone, is is named the King of Gems. Both the Bible
and ancient Sanskrit writing depict the ruby as
the most precious of all gemstones. To the Hindus, Ruby burned
from an inextinguishable internal fire.
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Rutilated Quartz
Rutilated Quartz is a transparent Colorless or light Smoky
Quartz with Rutile needles running through the stone. The needles
are usually Gold or Red. It is also known as Venus Hair Stone
or Cupid's Darts. Most Rutilated Quartz comes from Brazil.
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While Sapphire has
become the ultimate blue stone, it actually comes in virtually
every color except red (red Sapphires are Ruby Rubies),
including colorless and white, and such fancy colors as yellow,
peach, orange, cognac, pink, violet, purple and green and all
their many shades. In fact, white Sapphire has
become a popular natural Diamond Diamond substitute
for many people. Moreover fancy color Sapphire often
provides an alternative to other gems in
similar colors that are less durable. It is considered the
most important and versatile of the gem families. Sapphire ,
sister to Ruby ,
is known in the mineral world as corundum, which is a crystal
structure composed of aluminum oxide. On the Mohs scale of
hardness, Sapphire ranks
9, the highest in the gem world after diamond. It is considered
very durable, a great choice for rings and bracelets that are
prone to knocks. Although Sapphire is
not as brilliant as diamond, it has striking luster. Like Ruby , Sapphire may
be found in a translucent variety that may display a six-rayed
star effect when cut into a cabochon (dome) shape. This type
is known as star Sapphire ,
of which there are numerous synthetics on the market.
Natural gem-quality sapphire is
found in many parts of the world, but the rarest gems are
from Kashmir and Myanmar (Burma), most prized because their
color is closest to pure spectral blue. Fine Sapphire is
also produced in Sri Lanka in limited supply, both in blue
and fancy color. Sapphire is
also found in Thailand, Cambodia, Tanzania, Madagascar, Australia
and the United States (Montana).
Perfect natural gems in
color and appearance are very rare and expensive. Controlled
heating is commonly used in the trade to produce, intensify
or lighten color and/or improve clarity in many gems including
blue and fancy sapphire. This allows the trade to bring more,
better quality gems to
the market. Heat enhancement is permanent and stable. You can
clean heated (and non-enhanced) sapphire with
soapy water or commercial solvent and a brush. Mechanical cleaners
are also safe, except for heavily included gems (filled
with fissures).
Sapphire ,
September's birthstone, has been the pre-eminent blue gemstone for
centuries. Ancient Persian rulers believed its reflection painted
the heavens blue. Indeed, its very name in Latin, sapphirus,
means blue.
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Sapphirine
Sapphirine's name alludes to its Sapphire Blue
color, but the name and color are where the similarity ends.
Sapphirine has a hardness of 7.5 in a deep grayish Blue color.
Our stones are from Asia.
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Scapolite
Scapolite received its name from the Greek "skapos" for
shaft due to the stubby nature of its crystal growth. The Scapolite
series is composed of Silicate of Aluminum with Calcium and
Sodium. The crystals are typically found in metamorphic rocks
and are formed in the tetragonal system.
The first Gem Scapolite was found in Burma in 1913 and was
cut as a Cat's Eye. In 1920 transparent Golden Scapolite was
found in Madagascar with Brazil uncovering a find ten years
later. Modern sources for Scapolite also include Kenya, Tanzania,
Madagascar and Russia.
Scapolite has a hardness of 6-6.5 and is appropriate for jewelry with
proper care. This beautiful stone is available in several colors:
Colorless, Golden and Purple.
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Scheelite
Scheelite is a very brilliant stone with dispersion and luster
near that of Diamond. It has a hardness of 4.5-5. Our faceted Gems from
China are Yellow to Gold Yellow or Colorless, all expertly
cut. Scheelite was named for Karl Wilhelm Scheele, a Swedish
chemist.
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Silica Chrysocolla
Silica Chrysocolla is a Cryptocrystalline Quartz which is found
near Copper deposits. Primary sources are Arizona, New Mexico,
and Mexico. Our Cabochons, mined in Arizona, are a lovely Blue
to Blue/Green color. Chrysocolla is a durable stone, suitable
for jewelry, as well as for carvings.
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Sillimanite
Sillimanite is available in faceted stones or cabochons (also
known as Fibrolite, when found as cat's eye gemstones). Sillimanite
has a hardness of 6.5-7.5 and is found in southeast Asia.
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Sinhalite
This rare Gem is named for the Sanskrit word for the island
of Ceylon or Sri Lanka where it is found. It wasn't until 1952
that Sinhalite was determined to be a new mineral. It had been
confused with Citrine and Peridot until that time. Sinhalite
has a hardness of 6.5-7, so it can be mounted for jewelry Sinhalite
is available in bright slightly greenish Yellow or slightly
brownish Yellow.
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Smithsonite
Produced as a secondary mineral in ore deposits, Smithsonite
was named for James Smithson, the benefactor of the Smithsonian
Institute. Smithsonite has a hardness of 4-4.5 and obvious
doubling due to its extremely high birefringence.
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Spessartite Garnet
The Spessartite Garnets found in the Little Three Mine in Ramona,
California, are considered to be the world's finest. Their
vivid Orange color, sometimes with a Golden tone, is the most
desired. This American Gem is very rare in cut stones larger
than 3 carats.
The Little Three Mine has been worked for Spessartite since
1903, but production has been sporadic at best. The labor involved
is arduous because the crystals are buried in pockets in pegmatites,
once molten lava. The owner/miner slowly moves from pocket
to pocket to retrieve the crystals. The future of Little Three
Mine is currently threatened by the encroachment of subdivisions
around the mine. Mining will eventually be halted due to EPA
regulations.
Spessartite received its name from the area in Germany, Spessart,
where it was originally found in the 1800's. Since all Garnets
are tough wearing stones, Spessartite is appropriate for jewelry All
of our Gems are
bright, well cut, rare stones and many are of exceptional size.
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Sphalerite
Sphalerite is a mineral species which grows in the cubic crystal
system. Major sources are Spain and Mexico. It is available
in Green, Yellow, Brown, Orange, Red and Colorless with Red
and Orange being the rarest. Sphalerite is a singly refractive
stone with a hardness of 3.5 to 4. It has a strong dispersion
rate of 0.156 as compared to Diamond's 0.044. This means that
Sphalerite has "fire" when viewed in strong light.
Our inventory of Sphalerite was cut from a crystal from Spain.
These Gems are
bright and well cut. Matched pairs are also available.
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Sphene
Sphene is a rare and unusual Gemstone that
you will seldom see in any local jeweler's showcase. This Gem
has intense colors: golden Yellow, honey Brown or Yellow/Green.
Sphene's rich colors are highlighted by its high dispersion
or spectral fire. Sphene's dispersion rate is 0.51 as compared
to Diamond's 0.04. And like Diamond, Sphene has a high luster
making it a brilliant Gem. Fire and brilliance add up to a
great looking Gemstone for
mounting.
Sphene has a hardness of 5 to 5.5 and can be mounted with proper
care. Sources for this mineral are Baja, Mexico, Madagascar,
India and Brazil, although none have an abundance of rough.
Its name is from the Greek spenos, meaning wedge shaped.
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Spinel
CHEMISTRY MgAl2O4
CRYSTALLOGRAPHY Isometric
REFRACTIVE INDEX 1.712 - 1.717, normal. Reds may go up
to 1.735 and blues to 1.747.
HARDNESS 7.5 - 8
SPECIFIC GRAVITY 3.58 - 3.61
CLEAVAGE None
HEAT SENSITIVE No
WEARABILITY* Excellent
SPECIAL CARE INSTRUCTIONS None
ENHANCEMENTS None
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Spodumene
The most recognized member of the Spodumene mineral group is
Kunzite. But this group also includes the rare Hiddenite, Green
Spodumene and Yellow Spodumene. Hiddenite is especially difficult
to locate in the markets, and Green and Yellow Spodumene are
also hard to find.
Spodumenes have a hardness of 6.5-7.5. Its crystals grow in
the monoclinic system as flat, jagged prisms. Since Spodumene
has perfect cleavage, it is a very difficult Gem to facet.
This vibrant mineral was named for the Greek spodumenos, meaning "burnt
to ashes," a reference to the Gray color of the nonGem
crystals
Yellow Spodumene
Yellow Spodumene is often called Triphane. Our medium Yellow
Spodumenes are transparent, faceted with no visible inclusions.
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Star Ruby
A Cabochon with a Star is one which displays a 4 or 6-leg Star
when direct natural or incandescent light hits the top of the
Cab. Generally the brighter or more direct the sunlight, the
better the Star. A pen light is a must when examining Star
stones indoors. By rotating the light around the stone, you
can see the Star move across the surface of the stone.
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Sugilite
Sugilite is found in only one mine in the Kalahari Desert near
Hotazel, Africa. This area is known as the Kuruman Manganese
Field. The Wessel Mine is the only Gem Sugilite producer. Sugilite
was discovered there in 1975.
Sugilite is a grape jelly Purple opaque material, generally
cut in Cabochons or used as a carving medium. This mineral
forms in layers and banding is common. Commercial quality is
frequently mottled with White Chalcedony. Sugilite has a hardness
of 6-6.5 and is frequently mounted in jewelry
Sugilite has been highly promoted under the trade names "Royal
Lavulite" and "Royal Azel." See COLOR ENCYCLOPEDIA
OF GEMSTONES, Ed. II color plate 218. This is a HIGHLY RECOMMENDED
purchase. Price per carat indicates the stone's brightness
and intensity of the color.
CHEMISTRY (K,Na)(Na,Fe+3)2(Li2Fe+3)Si12O30 + Mn
CRYSTALLOGRAPHY Hexagonal, microcrystaline.
REFRACTIVE INDEX 1.607 - 1.610
HARDNESS 6 - 6.5
SPECIFIC GRAVITY 2.74, variable
CLEAVAGE None
HEAT SENSITIVE ?
WEARABILITY* Very Good
SPECIAL CARE INSTRUCTIONS Avoid rough handling
ENHANCEMENTS None
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Sunstone
SUNSTONE is the State Gem of Oregon, which is a prime source
for this beautiful Gem. Generally SUNSTONE shows a "Schiller" effect
where the metallic inclusions reflect light in a blaze of color.
Cleaner Red SUNSTONE is MUCH, MUCH rarer and commands true Gemstone prices!
It is a rare and sought after collector's item.
Oregon Red Sunstone differs from Sunstones found in other worldwide
locales in color, a strong pleochroism, and a glittering Schiller
effect created by pure native copper. In fact, the presence
of these bright inclusions was the reason for naming it Sunstone
or Heliolite, from the Greek helios for sun and lithos for
stone.
Faceted Oregon Sunstone is a transparent Gemstone that
was formed in basaltic lava flows. Sunstones are mined from
the surface from partially decomposed rock with a pick and
shovel. Shallow pits are dug to retrieve the rough. Unweathered
deposits release rough only by blasting and tunneling which
often shatters the Sunstone rough. The mining season averages
approximately six months.
Oregon Red Sunstone is an unusual American Gem distinguished
from other Feldspars by its unique chemical and physical properties.
It is a bright Gem, with or without the Schiller effect, that
creates outstanding jewelry
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Synthetic Alexandrite
Synthetic Alexandrite has come into the market in greater abundance
in recent years and is produced by the Czochralski or "pulled" method
and by the "floating zone" or "floating point" method.
It is more realistic and more expensive than the cheap color
changing Verneuil corundum that has usually been used as a
substitute for alexandrite.
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Synthetic corundum
Synthetic corundum, in the form of synthetic ruby, was the
first gemstone reproduced
by artificial techniques. Auguste Victor Louis Verneuil invented
the flame-fusion technique (now know as the Verneuil method)
of melting aluminum oxide and allowing it to recrystallize
in a cone-shaped boule, the color of which can be controlled
by the addition of chemical additives. This material is abundantly
and inexpensively created and used routinely in class rings,
birthstone rings, etc. Such material is rather easy to distinguish
from natural material by the presence of curved growth striations
and spherical gas bubbles or by the Plato method, in which
repeated twinning lines appear when the material is immersed
in high R.I. (refractive index) liquid and examined under magnification
between crossed polarized filters.
Other methods of growing synthetic corundum, such as flux-grown,
Czochralski pulled, and hydrothermal methods, produce more
realistic imitations, which are primarily identified by characteristic
inclusions. They are much more expensive than the Verneuil
synthetics but considerably cheaper than the rubies and sapphires that
they imitate.
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Synthetic Diamond
Synthetic Diamond is
produced under high pressure and temperature and, to date,
has not been produced at low enough costs to be used as a natural diamond substitute.
However, there are indications that we may begin to see gem
quality synthetic diamonds within
the next few years. Synthetic diamond is
used very extensively (two-thirds of the world production)
for industrial purposes as abrasive diamond grit.
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Synthetic Opal
Synthetic opal, coral, lapis lazuli, jade, turquoise, and quartz
have only in the past few years appeared on the market in fairly
good imitation of the natural material. Microscopic examination
usually reveals their identity. Recently, synthetic amethyst
has become very abundant, mixed into parcels of natural stones;
it can usually be detected by the absence of twinning, but
recent improvements in synthesis are making it more difficult
to detect, and the relatively low cost of both natural and
synthetic amethyst makes it prohibitively expensive to do routine
testing of large quantities of amethyst.
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Synthetic spinel
Synthetic spinel is produced by the Verneuil method and is
used most often to imitate stones other than spinel, such as
blue sapphire or
aquamarine. It is easily identified by its R.I., spherical
gas bubbles, and characteristic strain lines seen between polarizing
filters. It is quite inexpensive and widely used in inexpensive jewelry
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Taaffeite
Taaffeite, pronounced Tar fité, was discovered in 1945 by Count
Edward Taaffe and was named in his honor. Less than 300 Taaffeites
are known to exist! Our stones are from Sri Lanka and are in
shades of Mauve. Taaffeite has a hardness of 8 to 8.5.
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Tanzanite
Few gems have
attained the popularity of Tanzanite in such a short period
of time. The gem was only discovered in the 1960's and soon
the demand raised the prices to a very respectable level. The
government of Tanzania promoted this gem with an expertise
that would make DeBeers proud.
In 1995, while the Internet was still young, I received an
email from a college student in Canada. He was commissioned
by the Tanzanian government to assess what could be done to
raise the demand in Canada. I was surprised, because the demand
was already exceeded the supply.
Tanzanite is a beautiful gem, but with moderate hardness and
perfect cleavage, it is less than ideal for wearing in jewelry Its
closest look-alike, iolite, much better and costs less. Therefore,
much credit has to be given to a world-class promotion of this
gemstone.
The source for tanzanite is one small area in Tanzania. All
the upper layers have been worked and the latest sources are
from substantial depths. The mines closed right after the 1998
Tucson show. Heavy rain, flooding and cave in caused several
dozen deaths.
To reopen the mines requires considerable reinforcement. None
of the local miners will go back into the holes, so a foreign
crew would have to be brought in. Several large corporations
have looked into taking over the mines, but none have attempted
it because the cost is too great.
Even though the supply dried up, the demand for tanzanite remains
high. New sources have been discovered that are somewhat removed
from original source. However, the deposits are small and the
production is not nearly enough to equal demand. Prices have
skyrocketed and are expected to remain high for several years.
They will not go down until the demand for this gem finally
settles.
Since the mines closed, prices have varied wildly. Before closing,
top quality tanzanite, in the one to three carat range, wholesaled
for $100 a carat and would retail between $175 and $300. Today, gems in
the same size range, with moderate color saturation and eye
visible inclusions, typically sell around $400 a carat. Fine
quality gems can
demand over $1000 per carat.
Tanzanite is a variety of zoisite, which is a member of the
epidote group. The particular coloring that distinguishes tanzanite
is only found in Tanzania. As it comes from the ground, it
is primarily brown, although many stones show some purple.
By heating the stones to approximately 700 degrees Celsius,
a pleasurable color change takes place.
The quality of rough can be evaluated by its saturation. The
saturation doesn't change during heating; it just goes from
brown to purple and blue. So the deeper the saturation before
heating, the higher quality your finished goods will be.
After heating most tanzanites are just purple, with approximately
1/3 of the pieces having a blue direction. About half of these
will be oriented so you can get maximum yield cutting for the
blue color, or about 1/6th of each lot. Every once in a while
you will also find a very rare green tanzanite.
Blue tanzanites are more desirable than the purple. Before
the mines closed, they brought a higher price. Now the distinction
between blue and purple gems no
longer has a substantial affect on the price.
CHEMISTRY Ca2Al3(SiO4)3(OH)
CRYSTALLOGRAPHY Orthorhombic
REFRACTIVE INDEX 1.692 - 1.700
HARDNESS 6 - 7
SPECIFIC GRAVITY 3.35
CLEAVAGE Perfect
HEAT SENSITIVE Yes
WEARABILITY* Good
SPECIAL CARE INSTRUCTIONS Avoid rough treatment
ENHANCEMENTS Virtually all tanzanite is heat treated
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Tektite / Moldavite
This natural Glass is believed to have originated from meteorites
which fell to the Earth. Tektites are found in 4 major fields:
Czechoslovakia, Australia/Southeast Asia, the Ivory Coast of
West Africa and south/southeastern North America. Some of the
inclusions generally found in this natural Glass are gas filled
bubbles and vesicles, a contorted swirling internal structure,
small grains or curved "tails" of pure silica Glass,
Iron/Nickel spherules and shocked mineral inclusions.
Tektites are found in the four major areas of the world, but
Moldavite comes only from the Moldau River Valley in Czechoslovakia
in what is called the Ries Crater. Chemical analysis dates
this Tektite Crater to 14.7 Million years! Our faceted moldavites
are transparent medium to medium dark Green. Moldavite has
a hardness of 5.5-6.6. It has been used since prehistoric times
as jewelry, tools, and religious artifacts.
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The Story of Red Spinel
If you have ever been to London and seen the British Crown
Jewels, you will have noticed the giant red gemstone set
in the center of the Imperial State Crown. This stone, quite
possibly the most famous gem in the entire world, is the Black
Prince's Ruby. As large as a hen's egg, weighing approximately
170 carats, and measuring five centimeters in length, the Black
Prince's Ruby is
a spectacular red, and it seems to glow with an internal fire
of its own. It is so remarkable that it has become one of the
world's most cherished jewels. But did you know that the Black
Prince's Ruby really
isn't a ruby at
all? It's actually a spinel, and it has a long and fascinating
history.
The gem's first known owner was Abu Said, a Moorish prince
of Granada in Spain in the mid-1300s. Abu Said lost the gem,
as well as his crown and his life, to Don Pedro the Cruel
of Seville. In 1366 Don Pedro's own brother attacked him
in turn, but Don Pedro successfully defended himself with
help from the armies of the Black Prince of Bordeaux. As
payment, the Black Prince demanded Don Pedro's prize jewel,
and Don Pedro was in no position to argue.
>How the Black Prince's Ruby came
to England is unknown, but it made its next historical appearance
in a jeweled helmet worn by the English king, Henry V, at
the Battle of Agincourt in 1415. The helmet saved Henry's
life when a blow from the battleaxe of the French duke of
Alencon nearly destroyed it. Both the king and the helmet
miraculously survived the war, and the Black Prince's Ruby remained
in English hands.
Later, King James the First had the gem set into the state
crown, and, despite many threats of theft, fire, and even
Nazi bombs, over the centuries the Black Prince's Ruby has
remained the magnificent centerpiece of the British royal
regalia.
While the Black Prince's Ruby is
by far the world's most famous red spinel, it is definitely
not the only one ever possessed or coveted by kings, queens,
and emperors. The Timur Ruby, also in the Crown Jewels of
England, is even larger, weighing 361 carats, or more than
70 grams. It is inscribed with the names of six of its former
owners. The Kremlin Museum in Moscow has another giant gem
that probably belonged to the Tsar; this one weighs 414 carats.
The most dazzling collection of fine red spinels is found
in the Crown Jewels of Iran. The majority were plundered
from India when the Mogul Empire fell. The largest one weighs
about 500 carats, and it is indeed the biggest on record.
Many others weigh over 100 carats, and more than a dozen
have been carved with the name of Jahangir, a Mogul emperor
over 350 years ago.
Once you have seen a fine red spinel, you will easily understand
why ancient royalty esteemed it as much as ruby, and sometimes
even more. Top quality red spinels and rubies have
superb pure red colors, and they actually fluoresce, or glow,
in natural light. These similarities led to some confusion
in early history when people classified gems only
by their colors. They called all blue gems sapphires,
all green gems emeralds,
and all red gems rubies;
spinels were called
"Balas rubies," after a region in northern India
known as Balascia, where they were first reportedly mined.
Later, when people learned that gems of
the same color are not necessarily the same kind of material,
they still had difficulty separating red spinel and ruby.
Not only do the two gems have
the same color and fluorescence, but they are often found
together in the same mines, and ruby's physical properties
are very similar to spinel's; ruby is
only slightly more dense and slightly harder. (Spinel is
actually as hard or harder than emerald, topaz, quartz, and
all but five other natural minerals.)
Despite its fame in the ancient world, red spinel has never
been as abundant as ruby, and today it is quite difficult
to find. The old mines in Afghanistan that produced so many
of the giant stones in the Moguls' collections seem to have
been worked out, and the gem gravels of Sri Lanka and Africa,
which give up many beautiful pastel colored spinels, only
rarely contain gems with
the pure intense red color of the Black Prince's Ruby.
Now only the famous mines of Mogok, Burma, hold substantial
quantities of fine red spinels. Jealously guarded by the
Burmese kings until 1885, controlled by a monopoly under
the British Empire, and then nationalized by a socialist
government in 1962, Mogok's mines have scarcely had a chance
to live up to their potential. While a few beautiful red gems have
been smuggled out through the gauntlet of jungle, opium warlords,
rebels, and soldiers that makes up the Burmese hinterland,
these exquisite gems have
only been able to offer enticing hints of the sumptuous jewels
that must still lie hidden in the mountains of Mogok. No
one really knows how many gems remain
there undiscovered, but perhaps there is still one that will
rival even the Black Prince's Ruby and
remind us all of the days when kings and emperors held sway
over vast domains and counted their wealth by the natural
beauty that they owned.>
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Tigers Eye
CHEMISTRY SiO2
CRYSTALLOGRAPHY Hexagonal, microcrystaline.
REFRACTIVE INDEX 1.544 - 1.553
HARDNESS 7
SPECIFIC GRAVITY 2.651
CLEAVAGE None
HEAT SENSITIVE No
WEARABILITY* Very Good
SPECIAL CARE INSTRUCTIONS None
ENHANCEMENTS Can be heated, dyed or bleached. Occasional.
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Topaz
Topaz, the birthstone for November, is available in several
different colors: Colorless or White, Blue, Yellow to Orange
and Pink. Many consumers are aware of only the Blue shade due
to the current popularity of Blue Topaz in jewelry Colorless
Topaz is found in many locales worldwide. Although some Blue
Topaz is produced in nature, the natural shade is generally
too pale to excite any interest. The Blue Topaz readily available
in the market actually began as Colorless Topaz and was irradiated
to produce the vibrant Blue Shades. Then it was heated to stabilize
the color.
Natural Pink Topaz is very limited, although a bright Pink
treated Topaz from Pakistan came into the market a few years
ago. It is not considered to be a stable color. Brownish Yellow
to Yellow Topaz is the least expensive stones of the Yellow
hues. The medium Golden and peachy Orange shades are more vibrant,
more desirable and more expensive. The sherry Red, deep Pink
and reddish Orange colors, referred to as "Imperial" Topaz,
are the most desired and most expensive of the Yellow tones.
Topaz crystals grow in the orthorhombic shape and are usually
terminated at only one end.
Crystals occur in cavities of highly acid igneous rocks, generally
in pegmatite dykes. A dyke is formed when hot magma began rising
from the earth's center. Instead of erupting as a volcano,
the magma slowly cooled into granite masses where it fractured
the earth's crust. The mining process is an arduous one. It
involves moving tons of earth to form terraces near productive
veins. Then picks and shovels are used to dig into the terrace
in search of crystals. Each shovel of dirt must be examined
for crystals before it is carried away so the dig can continue
unhindered. This is daylight to dark, backbreaking work for
which the miners are paid very little.
Although Topaz of any color is the birthstone for November,
other Gemstones have
also been used as a November birthstone substitute. Previously
Yellow was the dominant color used in birthstone jewelry But
many of the stones used by manufacturers in these inexpensive
settings were actually Citrine, a Yellow variety of Quartz.
Smoky Quartz was also called Smoky "Topaz" by many
unscrupulous persons and unknowing jewelers in an attempt to
create more sales in this birth month. Unfortunately Smoky "Topaz" is
still a very cheap variety of Quartz and not the more precious
Topaz.
The hardness of Topaz is 8. It is a very bright and attractive
Gem that is appropriate for any kind of jewelry All jewelry should
be well cared for, and Topaz jewelry should
be cleaned in warm, soapy water.
CHEMISTRY Al2SiO4(F,OH)2 + Cr
CRYSTALLOGRAPHY Orthorhombic
REFRACTIVE INDEX 1.607 - 1.627
HARDNESS 8
SPECIFIC GRAVITY 3.53 - 3.56
CLEAVAGE Perfect one direction
HEAT SENSITIVE No
WEARABILITY* Very Good
SPECIAL CARE INSTRUCTIONS None
ENHANCEMENTS Pink or Red, may be heat treated. Most blue
topaz has been irridated and heat treated.
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Tourmaline
Tourmaline is a large family of Gemstones with
more than 100 hues available. Its name comes from the Sinhalese
turmali, meaning mixed Gemstones due
to the tendency to confuse Tourmalines with other Gems. Tourmaline
from Ceylon was first introduced to the Europeans in the late
1600's or early 1700's by Dutch traders. It was believed to
promote continued good health, so it became a favorite jewelry stone.
Tourmalines were also attributed the ability to build valuable
friendships and business contacts, to enrich knowledge and
intuition and to create harmony and social popularity.
Tourmaline crystals grow in the hexagonal shape and tend to
be long, pencil shape crystals. This crystal shape is the reason
why long rectangular cuts are so frequently seen in Tourmaline.
Many Tourmalines exhibit pleochroism, the variation of colors
visible in different axial directions of the crystal. The cutter
must always cut the table parallel to the main axis to produce
a stone with vivid color.
All Tourmaline crystals begin as Colorless. Colors are absorbed
when trace elements of seeping liquids replace the normally
present atoms. Tourmaline takes a wider variety of colors from
these trace elements than any other Gem.
A pocket of Tourmaline crystals may contain one of several
different colors. Tourmaline crystals are often cracked and
flawed, especially in the Red, Pink and Bi-colors. Clean stones
of 10 Carats or more in these colors command a premium price.
The Green and Blue colors are generally very clean.
Tourmaline is a good jewelry stone.
It has a hardness of 7 to 7.5. All Tourmaline jewelry should
be stored in a separate compartment or in a jewelry bag
to prevent scratching by harder Gemstones. Tourmaline jewelry should
be cleaned in warm, soapy water with a soft brush. Any of the
Tourmaline colors can be used as one of the birthstones for
October. Tourmaline is also the 8th wedding anniversary Gemstone.
CHEMISTRY Elbaite, Na(Li,Al)3Al6B3Si6O27(OH)3(OH,F)
CRYSTALLOGRAPHY Hexagonal
REFRACTIVE INDEX 1.603 - 1.655
HARDNESS 7 - 7.5
SPECIFIC GRAVITY 2.84 - 3.10
CLEAVAGE No
HEAT SENSITIVE Some
WEARABILITY* Very Good
SPECIAL CARE INSTRUCTIONS Multicolored gems are
often weak where the colors meet
ENHANCEMENTS Heat treatment, common on dark gems, otherwise
occasional. Irridation, occasional.
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Tsavorite Garnet
Tsavorite is the intense Green Grossular Garnet named after
the Tsavo National Park in Kenya. Tsavorite was first discovered
in 1967 and was named by Henry B. Platt, vice-president of
Tiffany & Co., after the site of that find.
Tsavorite is often compared to other Green Gemstones, and it
is easily a match for the better known Emerald. Actually Tsavorite
is superior to the Emerald in
many ways, and it is a rarer stone. Tsavorite is a tougher,
more durable stone with a higher luster, resulting in a higher
polish. It also has a higher refractive index, 1.74 for Tsavorite
compared to 1.57 for Emerald. This indicates that Tsavorite
is the brighter stone for setting with Diamonds since
the Tsavorite will display more sparkle and fire.
The Green color of Tsavorite comes from Vanadium with a slight
trace of Chromium. Shades vary from pure Green to yellowish
Green. Like Emerald, most Tsavorites will have some visible
inclusions. Most Tsavorite production is under 1 Carat. A 2
Carat Tsavorite is considered large!
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Tugtupite
Tugtupite is a rare Gem from Greenland. It is often called
the Reindeer Stone because tugtup means reindeer in their language.
Tugtupite was discovered in 1960 and is coveted by collectors
of fluorescent minerals.
This Gem fluoresces strong Orange under long wave ultraviolet
light and strong purplish Red under short wave ultraviolet.
The opaque material is generally rosy Pink with White mottling
and is used for carvings and Cabochons. Tugtupite can combine
three colors: White, Pink and Gray. The less White and Gray
and the more intense the Pink, the higher the price.
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Turquoise
Turquoise has been valued throughout history for its beautiful
color which ranges from Green to Blue with pure Blue being
the most expensive. It was used by the Pharaohs as early as
1000 B.C. for ornamentation. Turquoise amulets adorned horse
bridles because it was believed to keep the animals surefooted.
In ancient Native American lore, the Blue of Turquoise was
thought to represent the sky and atmosphere above Mother Earth.
Thus Turquoise was connected to the breath of life. Turquoise
is considered a balancing and healing source of energy.
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Watermelon Tourmaline
Sometimes the mineral deposit in the Tourmaline crystal will
form a color band along its length or width which will then
be appropriately called Bi-color, Tri-color or Watermelon if
the colors are Green and Red with a White separation. The vast
majority of the stones are obscure or heavily included. Clean Gems are
much more expensive.
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Wulfenite
This Gem was named for Franz Xavier Wulfen, an Austrian mineralogist.
Wulfenite has a hardness of 2.5-3 and has a very high dispersion
rate of 0.203, which is 5 times greater than that of Diamond.
Our 4.09 Cts. Wulfenite is brilliant Orange, almost eye clean
and comes from the Red Cloud Mine in Arizona. It is well faceted
with absolutely beautiful uniform color. This may be the best
Wulfenite in the world!
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Xenotime
The research is sketchy on this mineral. This faceted stone
is from Brazil. It is transparent dark Brown with moderate
eye visible inclusions. If you've ever seen Chrysanthemum Stone
carvings, you've seen Xenotime as part of the radiating flowers.
Xenotime is yttrium phosphate and has a hardness of 4-5. It
has perfect cleavage which makes it extremely difficult for
a cutter to facet.
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Spodumene
The most recognized member of the Spodumene mineral group is
Kunzite. But this group also includes the rare Hiddenite, Green
Spodumene and Yellow Spodumene. Hiddenite is especially difficult
to locate in the markets, and Green and Yellow Spodumene are
also hard to find.
Spodumenes have a hardness of 6.5-7.5. Its crystals grow in
the monoclinic system as flat, jagged prisms. Since Spodumene
has perfect cleavage, it is a very difficult Gem to facet.
This vibrant mineral was named for the Greek spodumenos, meaning "burnt
to ashes," a reference to the Gray color of the nonGem
crystals
Yellow Spodumene
Yellow Spodumene is often called Triphane. Our medium Yellow
Spodumenes are transparent, faceted with no visible inclusions.
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Zircon
Zircons are natural Gemstones available
in an array of colors. It is one of the birthstones for December.
Zircon's name comes from the Arabic zargoon, meaning vermilion.
Zircon was worn by the ancients as amulets protecting travelers
against the plague, wound and injuries. It proportedly guarded
sailors from lightning and expelled evil spirits through its
brightness.
Natural Zircons are one of the few Gemstones with
dispersion or fire. Zircon approaches Diamond in
fire, so the Colorless Zircon has been a successful natural
substitute for Diamond. A composite of silicate of zirconium,
Zircon forms in the tetragonal crystal system. The crystals
usually are in the form of a double pyramid. Zircon has a hardness
of 7-7.5 on the Mohs scale.
Zircon is found worldwide, but the major sources are Sri Lanka,
Myanmar, Thailand and Vietnam. Colorless, Blue, Green, Golden,
Red, Rose and Fancy colors provide an ample choice of colors.
For an illustration of Zircons, see the COLOR ENCYCLOPEDIA
OF GEMSTONES Ed.
I, color plate 64; Ed. II, 247. Zircons are beautiful, natural Gemstones which
are currently underpriced in the Gem markets.
CHEMISTRY ZrSiO4
CRYSTALLOGRAPHY Tetragonal
REFRACTIVE INDEX Low, 1.78 - 1.85. High 1.92 - 2.01
HARDNESS Low 6 to 7.5 high
SPECIFIC GRAVITY Low 3.9 - 4.1. High 4.65 - 4.80
CLEAVAGE Imperfect
HEAT SENSITIVE No
WEARABILITY* Good
SPECIAL CARE INSTRUCTIONS Facet edges wear off, caution
if putting in a ring.
ENHANCEMENTS Virtually all blue zircon is heat treated.
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Zoisite
Zoisite is the mineral group that includes Tanzanite. It has
a hardness of 6 to 7 and is available in several colors. The
green Zoisite is particularly difficult to locate in quality
material.
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