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Copyright
© 2008
Gold Miner Jewelry
All rights reserved
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| Gem
Guide |
Alexandrite
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Alexandrite changes from green to red,
mauve or brown in incandescent light. Alexandrite has a hardness
rating of 8.5. There are many many synthetic alexandrites on the
market. Natural alexandrite is very rare. Alexandrite is found
in Brazil, Madagascar, Myanmar, Russia, Sri Lanka and Zimbabwe. |
Amethyst
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Amethyst is purple quartz and
is one of the most popular gemstones. It varies from pale
lavender to deep purple with red highlights. Amethyst is
generally abundant and quite inexpensive. Amethyst is purple,
lilac or mauve. The highest quality is transparent. It has a
hardness of 7. |
Aquamarine
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Aquamarine is light blue, blue-green and
dark blue. The highest quality is transparent. It has a hardness
of 7.5. Aquamarine often becomes paler if left out in the
sun. |
Citrine
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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.
Darker colors are more highly prized, including medium golden
orange ("Rio Grande" citrine) and dark sherry-colored ("Madeira"
citrine). |
Diamonds
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Diamonds are slightly yellowish, and in
this general color range, those most approaching absolute lack
of color are most prized. However, brightly colored diamonds are
much rarer and more expensive. The deep blue Hope diamond and
blue Eugenie diamond, both in the Smithsonian collection, are
among the most famous examples. It has a hardness of 10. |
Emeralds
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Emeralds are medium to dark green beryl
which derives its color from chromium and vanadium. Emerald has
a hardness rating of 7.5. of fine color and clarity can be quite
expensive. The best known sources include Colombia, Zambia.
Almost all emeralds contain numerous small inclusions and
fractures that promote fragility. Most stones on the market are
impregnated with oils, waxes, or other substances to mask the
fractures and sometimes enhance color. |
Garnets
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Garnets usually dark brownish to purplish
red usually cut in small sizes (under 2 carats), as larger
stones appear black. Garnet ranges in color from colorless to
black though it is often thought of as only red. There are
various types of garnet with the hardness ranging from 7 - 7.5.
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Jade
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There are two types of Jade: Jadeite and
Nephrite. Jadeite is rarer and the highest quality is known as
imperial Jade. Jadeite comes in many colors: red, yellow, green,
lilac, black, orange, white, pink, blue and brown. Jadeite has a
hardness of 7. Nephrite Jade is more common and is often used in
Chinese carvings. Nephrite Jade comes in various tones of green
-- mostly with an olive green tone. It has a hardness of 6.5. |
Onyx
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Onyx is a rich-looking, affordable black
stone. It is often mixed with pearls to create elegant jewelry.
Onyx, sard, and sardonyx are all varieties of chalcedony (microcrystaline
quartz). Onyx comes in brown, white, grey, and black. Sard is a
reddish-brown variety. Sardonyx is a blend of sard and onyx with
the red bands of sard and the white bands of onyx. Onyx, sard
and sardonyx all have a hardness rating of 7. |
Opal
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Opal in large sizes are rare and costly,
especially black opal. Usually cut as cabochons, sometimes
beads. Occasionally found as fossilized (opalized) clamshells,
snail shells, or wood. Transparent opals, such as Mexican red or
orange fire opal, are often faceted. Values are normally
determined by the presence and nature of color flashes (play of
color). Opal's scratch hardness is measured at 6.0 to 6.5 on the
Mohs' scale, similar in hardness to quartz, a little more than
halfway between the hardness of talc and diamond. |
Pearls
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Pearls are formed in shellfish, as a
reactant to an irritant such as a piece of sand. Cultured pearls
are created by adding a piece of mussel or shell inside of an
oyster of mussel. This then creates a pearl as layers of the
inside of the shell grow over the added substance. The price of
pearls vary widely as a result of luster, size, how they were
grown, color and type. Natural pearls are the most expensive,
followed by cultured pearls. Fresh water pearls tend to be
relatively inexpensive. Pearls are generally white, brown,
silver, cream, black or pink depending on the type of shellfish
and water. Pearl has a hardness of 3. |
Peridot
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Peridot is a transparent lime or olive
green. It has a hardness of 6.5. As with all gems, protect
peridot from scratches and sharp blows. Also avoid large
temperature changes (such as leaving it be a heater vent or in a
hot car). Do not clean peridot in a home ultrasonic cleaner.
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Ruby
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Ruby may be any color of red depending on
the chromium and iron content of the stone. Ruby has a hardness
rating of 9. Generally, ruby is quite durable. Still, rubies are
subject to chipping and fracture if handled roughly. Ruby is
found worldwide. The finest stones are from Myanmar. Bright red
stones are mined in: Afganistan, Pakistan, Vietnam. Brownish-red
rubies are from Thailand. Darker stones are generally produced
from the mines in Australia, India, Russia and USA (Georgia,
North Carolina and Wyoming). |
Sapphire
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All gem quality corundum that is not red
is called sapphire such as blue, orange, yellow, violet, green,
white and pink. Unless a color is stated, sapphire is assumed to
be blue. Some sapphires (color change sapphires) will change
between blue and violet depending on the light. Sapphire has a
hardness of 9. Generally, sapphire is quite durable. Still,
sapphires are subject to chipping and fracture is handled
roughly. |
Tanzanite
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Tanzanite may be blue, purple or slate
gray. Tanzanite has a hardness rating of 6.5. Tanzanite is often
heat treated to improve its color and clarity. Tanzanite can
easily be scratched or chipped. Clean your Tanzanite with warm,
soapy water and a soft bristle brush. Avoid using ultrasonic
cleaning. |
Topaz
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Topaz comes in many colors such as blue,
yellow, pink, brown, green and clear. Orange-red "Imperial"
topaz is rare. Topaz has a hardness of 8. As with all gems,
protect topaz from scratches and sharp blows. |
Tourmaline
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Tourmaline comes in many colors such as
blue, yellow, pink, red, black, green and clear. It has a
hardness of 7.5. As with all gems, protect tourmaline from
scratches and sharp blows. |
Zircon
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Zircon is a natural stone - not to be
confused with Cubic Zirconia which is manmade. It is known as a
colorless stone used to imitate diamonds but also comes in:
blue, yellow, orange, red, brown and green . It has a hardness
of 7.5. Zircon is somewhat soft so avoid scratches and sharp
blows. Avoid hot water and household chemicals. |
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