The Gemstone Encyclopedia
Discover the world's most beautiful gemstones. Properties, origins, comparisons, and expert guides — all in one place.
Today's Gemstone
Obsidian
Semi-Precious Gems
Obsidian is a volcanic glass in black to iridescent varieties, used since the Paleolithic for sharp blades and traded widely by ancient cultures. Today fashioned into cabochons, carvings, and spheres.
Featured Gemstones
View all →Alexandrite
Hardness: 8.5
Almandine
Hardness: 7.0
Amazonite
Hardness: 6.0
Amber
Hardness: 2.0
Amethyst
Hardness: 7.0
Apatite
Hardness: 5.0
Aquamarine
Hardness: 7.5
Aventurine
Hardness: 7.0
Benitoite
Hardness: 6.0
Black Opal
Hardness: 6.0
Bloodstone (Heliotrope)
Hardness: 6.5
Carnelian
Hardness: 6.5
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