Gemstone Encyclopedia

Gem Silica: The Blue Chalcedony That Is Not Chrysocolla

The finest gem silica came out of an Arizona copper mine as a byproduct, and the supply ended when the copper economics changed. What the name gets wrong, why translucency sets the price, and how d...

Chalcedony Information

Chalcedony, the beautifully colored cryptocrystalline quartz that could be precisely carved into seals and amulets, was a treasured gem of the ancient world.

Green Quartz

Quartz is ancient, but its green is usually younger than the person wearing it. What prasiolite is, why green amethyst is the wrong name, and how to buy it honestly.

Cat's Eye Citrine: A Gemstone of Golden Beauty

Cat's Eye Citrine is a captivating gemstone known for its unique chatoyancy, a phenomenon created by fibrous mineral inclusions within the stone. When cut in a cabochon shape, these parallel fibers...