Gemstones Glossary

A | B | C | D | E | F | G | H | I | J | K | L | M | N | O | P | Q | R | S | T | U | V | W | X | Y | Z

A

Achroite: Colorless range 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.

B

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).

C

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

D

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.

E

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.

F

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

G

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)

H

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

I

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

J

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

K

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!

L

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

Lapis lazuli: opaque, blue semi-precious stone. Hardness of 5,5

M

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

Malachite: opaque, semi-precious stone (green-banded), Hardness of 4

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

O

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)

P

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

Q

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

R

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.

S

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

T

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

Tigerīs 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

U

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

Z

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