translucent to opaque, semi-precious variety of chalcedony (quartz)

rare mineral/gem (type of chrysoberyl) that appears to be different colors when viewed in artificial or natural light.

gemstone-group, including emerald, aquamarine, morganite, heliodor, bixbite and goshenite.

rounded cut (usually with a domed surface) - no facets

standard measure of gemstone-weight. One carat weights 0,2 gram.

usually colorless gemstone, hardness of 7 - 7,5

most expansive and rare variety (green) of garnet, hardness of 6,5 - 7,5

precious gemstone, made of compressed carbon, hardness 10

precious green gemstone, variety of beryl. Hardness of 7,5 - 8

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.

cutting and polishing of the gemstone surface

colored diamonds (all colors, except white), hardness of 10

group of minerals/gems that occurs in a wide range of colors. Hardness of 6,5 - 7,5

rare, valuable and attractive mineral (usually faceted)

opaque, silver to black colored semi-precious stone, hardness of 6,5

Variety of garnet, hardness of 6,5 - 7,5

International Gemological Institute

most valuable topaz-variety (golden-orange-pinkish), hardness of 8

semi-precious stone, often set as cabochon in best (green & translucent) quality. Hardness of 6 - 7

semi-precious stone, variety of quartz. Hardness of 6,5 - 7

pink variety of the mineral spodumene, hardness of 6,5 - 7

blue gemstone, mostly with color-zoning. Hardness 4,5 - 6 - very difficult to cut!

variety of the semi-precious feldspar-group (plagioclase). Hardness 6 - 6,5

opaque, blue semi-precious stone. Hardness of 5,5

orange variety of garnet (spessartite-group), hardness of 7 - 7,5

pink variety of beryl. Hardness of 7,5 - 8

semi-precious stone (transparent - opaque), hardness of 5

semi-precious variety of chalcedony (quartz). Hardness of 6,5 - 7

beautiful, pinkish-orange sapphire-color, rare found in Sri Lanka

very popular gemstone (3 major types), containing water (!). Hardness of 5,5 - 6,5

the second common mineral on earth, including amethyst, ametrine, citrine, rose quarz, aventurine, rock crystal, chalcedony, chrysoprase and many others

pinkish-red variety of garnet (combination of pyrope and almandine). Hardness of 7 - 7,5

colorless variety of quartz, also called white quarz. Hardness of 7

all color-varieties of corundum, except red. One of the most popular and expansive gemstones. Hardness of 9.

rare gem/mineral, ranging in color from colorless, yellow, greyish, greenish to brown. Hardness of 6,5 - 7,5

exclusive bluish-purple gemstone from Tanzania in East-Africa. Hardness of 6,5 - 7

exclusive green variety of garnet (grossular-group). Hardness of 6,5 - 7,5

opaque, semi-precious stone (containing granite, epidote and feldspar). Hardness of 6,5 - 7

natural gemstone, occuring in many different colours. Hardness of 6,5 - 7,5