Achroite
|
colorless variety of tourmaline.
Hardness of 7 - 7,5 |
Agate
|
translucent to opaque,
semi-precious variety of chalcedony (quartz) |
Alexandrite
|
rare mineral/gem (type
of chrysoberyl) that appears to be different colors when viewed
in artificial or natural light. |
Almandine
|
reddish variety of garnet.
Hardness of 6,5 - 7,5 |
Amazonite
|
semi-precious stone (blue
to bluish-green), variety of feldspar-family. |
Amethyst
|
most popular quartz-variety
(deep purple to pale lavender) |
| Ametrine |
(partially purple/lavender
and orange/yellow quartz-variety (amethyst and citrine). |
Apatite
|
semi-precious mineral
that occurs in many different colors, hardness of 5 |
Aquamarine
|
very popular (blue) variety
of the beryl-family |
Aventurine
|
semi-precious, translucent
variety of the quartz-family |
Beryl
|
gemstone-group, including
emerald, aquamarine, morganite, heliodor, bixbite and goshenite. |
Birthstone
|
worldwide assigned stones
to the months of the year |
Brilliant
Cut
|
faceted round cut (32
facets above the girdle, 24 facets below) . |
Cabochon
|
rounded cut (usually with
a domed surface) - no facets |
Carat
|
standard measure of gemstone-weight.
One carat weights 0,2 gram. |
Chalcedony
|
mostly milky or translucent
semi-precious stones of the quartz-family, including cornelian,
chrysoprase, onyx, jasper |
Charoite
|
semi-precious,opaque mineral
(purplish), only found in Russia |
Chrome-Diopside
|
intense green-colored
gemstone, hardness of 5 - 6 |
Chrysoberyl
|
yellowish to green and
brown colored gemstone, hardness of 8,5 |
Chrysocolla
|
opaque, blue to bluish-green
semi-precious mineral, hardness of 2 - 4 |
Chrysoprase
|
most valued, semi-precious
quarzt-variety (green) |
Citrine
|
pale yellow to orange
quarzt-variety. Hardness of 7 |
Clarity
|
clearness of gemstones |
Cornelian
|
semi-precious, tranlucent
variety (reddish) of chalcedony-quartz. |
Corundum
|
second hardest mineral
on earth (hardness of 9). Depending on the color there are
two precious varieties: ruby and sapphire |
Crown
|
upper part of a faceted
gemstone |
| Danburite |
usually colorless gemstone,
hardness of 7 - 7,5 |
Demantoid
|
most expansive and rare
variety (green) of garnet, hardness of 6,5 - 7,5 |
Diamond
|
precious gemstone, made
of compressed carbon, hardness 10 |
Doublet
|
gemstone made of two layers
- the upper part is usually the precious stone, the bottom-part
is semi-precious. |
| Emerald |
precious green gemstone,
variety of beryl. Hardness of 7,5 - 8 |
Enhanced
|
gemstones will be treated
to improve the color or clarity. Heat-treatment is very common,
all other methods (irradiation, coating, oiling, diffussion
etc) have to be declared. |
Facetting
|
cutting and polishing
of the gemstone surface |
Fancy
Diamond
|
colored diamonds (all
colors, except white), hardness of 10 |
Fancy
cut
|
Unusual cut (faceted or
cabochon) |
Feldspar
|
most common (semi-precious)
mineral-family on earth, hardness of 4 - 6,5 |
Fire
Opal
|
transparent opals (yellow,
orange, red), mostly milky. Hardness of 5,5 - 6,5 |
Fluorite
|
semi-precious mineral
that occurs in many colors, hardness of 4 |
Garnet
|
group of minerals/gems
that occurs in a wide range of colors. Hardness of 6,5 - 7,5 |
Gemstone
|
rare, valuable and attractive
mineral (usually faceted). |
GIA
|
Gemological Institute
of America |
Goshenite
|
Colorless variety of beryl.
Hardness of 7,5 - 8 |
Grossular
|
Variety of garnet, hardness
of 6,5 - 7,5 |
GLA
|
Gem Lab Austria (Vienna) |
Hematite
|
opaque, silver to black
colored semi-precious stone, hardness of 6,5 |
Hessonite
|
Variety of garnet, hardness
of 6,5 - 7,5 |
Hiddenite
|
yellow to green variety
of the mineral spodumene, hardness of 6,5 - 7 |
| IGI |
International Gemological
Institute |
Imperial
Topaz
|
most valuable topaz-variety
(golden-orange-pinkish), hardness of 8 |
Indicolite
|
blue variety of tourmaline.
Hardness |
Iolite
|
blue mineral/gem with
strong pleochroism, hardness of 7 - 7,5 |
Irradiation
|
radiation-treatment to
enhance colors of gemstones |
Jade
|
semi-precious stone, often
set as cabochon in best (green & translucent) quality.
Hardness of 6 - 7 |
| Jasper |
semi-precious stone, variety
of quartz. Hardness of 6,5 - 7 |
Kunzite
|
pink variety of the mineral
spodumene, hardness of 6,5 - 7 |
Kyanite
|
blue gemstone, mostly
with color-zoning. Hardness 4,5 - 6 - very difficult to cut! |
Labradorite
|
variety of the semi-precious
feldspar-group (plagioclase). Hardness 6 - 6,5 |
Lapis
lazuli
|
opaque, blue semi-precious
stone. Hardness of 5,5 |
Mandarin-Garnet
|
orange variety of garnet
(spessartite-group), hardness of 7 - 7,5 |
| Malachite |
opaque, semi-precious
stone (green-banded), Hardness of 4 |
| Mohs-scale |
This scale shows a chart
of relative hardness of various minerals (1 = softest, 10
= hardest).
| Hardness Example |
| |
|
| 10 |
diamond |
| 9 |
corundum (ruby, sapphire) |
| 8 |
beryl (emerald, aquamarine) |
| 7.5 |
garnet |
| 6.5-7.5 |
steel file |
| 7 |
quartz (amethyst, citrine, agate) |
| 6 |
feldspar (spectrolite) |
| 5.5-6.5 |
most glass |
| 5 |
apatite |
| 4 |
fluorite |
| 3 |
calcite, a penny |
| 2.5 |
fingernail |
| 2 |
gypsum |
| 1 |
talc |
|
Morganite
|
pink variety of beryl.
Hardness of 7,5 - 8 |
| Moonstone |
semi-transparent to translucent
variety of feldpar. It occurs in different colors (white,
pale yellow, grey, orange, brown and reddish) Hardness of
6 - 6,5 |
Obsidian
|
semi-precious stone (transparent
- opaque), hardness of 5 |
| Onyx |
semi-precious variety
of chalcedony (quartz). Hardness of 6,5 - 7 |
Opal
|
very popular gemstone
(3 major types), containing water (!). Hardness of 5,5 - 6,5 |
Opaque
|
light is not possible
to pass through (no brilliance) |
Padparadscha
|
beautiful, pinkish-orange
sapphire-color, rare found in Sri Lanka. |
Peridot
|
green gemstone of vivid
color. Hardness of 6,5 - 7 |
Pleochroism
|
the property of having
more than only one color, especially when the gemstone is
viewed from different angles. |
Precious
Stone
|
rare and valuable gemstone |
| Pyrope |
reddish variety of garnet.
Hardness of 6,5 - 7,5 |
Pyrite
|
opaque, semi-precious
stone (metallic). Hardness of 6 - 6,5 |
Quartz
|
the second common mineral
on earth, including amethyst, ametrine, citrine, rose quarz,
aventurine, rock crystal, chalcedony, chrysoprase and many
others. |
| Rhodolite |
pinkish-red variety of
garnet (combination of pyrope and almandine). Hardness of
7 - 7,5 |
Rock
Crystal
|
colorless variety of quartz,
also called white quarz. Hardness of 7 |
| Rose
Quartz |
pale pink to pink variety
of quartz (mostly silky). Hardness of 7 |
Rubellite
|
reddish variety of tourmaline.
Hardness of 7 - 7,5 |
Ruby
|
reddish variety of corundum.
Actually one of the most expansive gemstones. Hardness of
9 |
Rutilated
Quartz
|
Variety of quartz, containing
fine needles of rutile-crystals.
|
Sapphire
|
all color-varieties of
corundum, except red. One of the most popular and expansive
gemstones. Hardness of 9. |
Sillimanite
|
rare gem/mineral, ranging
in color from colorless, yellow, greyish, greenish to brown.
Hardness of 6,5 - 7,5 |
Smoky
Quartz
|
brownish (smoky) variety
of quarz. Hardness of 7 |
Sodalite
|
blue and opaque, semi-precious
stone, Hardness of 5,5 - 6 |
Spessartite
|
reddish or orange variety
of garnet. Hardness of 7 - 7,5 |
| Spinel |
attractive gemstone which
ranges in color from yellow to black. Hardness of 8 |
Sunstone
|
reddish-orange (metallic)
variety of feldspar (oligoclase). Hardness of 6 |
Tanzanite
|
exclusive bluish-purple
gemstone from Tanzania in East-Africa. Hardness of 6,5 - 7 |
| Tsavorite |
exclusive green variety
of garnet (grossular-group). Hardness of 6,5 - 7,5 |
Tiger´s
Eye
|
yellowish-brown, opaque
variety of the quarz-family. Hardness of 7 |
Topaz
|
popular gemstone, ranges
in color from colorless to yellow, to orange to pink and brown.
Hardness of 8 |
Tourmaline
|
the only gemstone which
occurs in all colours. Hardness of 7 - 7,5 |
Translucent
|
light is able to pass
through, but it is scattered. |
Transparent
|
light is able to pass
through without any diffusing |
| Turquoise |
semi-precious, opaque
stone with typical color. Hardness of 6 |
Unakit
|
opaque, semi-precious
stone (containing granite, epidote and feldspar). Hardness
of 6,5 - 7 |
Zircon
|
natural gemstone, occuring
in many different colours. Hardness of 6,5 - 7,5 |
