Tagged “commonly-treated”

Entries across every discipline that share this thread.

Gemstone

The sea-blue variety of beryl — emerald's clearer, hardier cousin, coloured by iron.

The yellow-to-orange variety of quartz — November's warm birthstone, most of it heat-made from amethyst.

The green variety of beryl — valued for its vivid colour despite near-universal inclusions.

The red variety of corundum — second only to diamond in hardness, and coloured by chromium.

Corundum in every colour but red — famed for its blue, and prized for durability.

A blue-violet zoisite found in just one place on Earth — heat-treated and pleochroic.

A hard aluminium fluorosilicate spanning colourless to imperial orange — with a notable cleavage to respect.

A sky-blue copper phosphate valued for millennia — soft, porous and often stabilised.

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