Sapphire

All other colour varieties of corundum apart from ruby are called sapphire. Sapphire comes in a large range of different colours from blue, pink, green, black, purple, yellow, colourless, green and many intermediary colours. Sapphires form either in metamorphic environments or in magmatic (basaltic) deposits. Main producing countries include Sri Lanka, Burma, Madagascar, Australia, Vietnam, Tanzania, Nigeria, Laos and Thailand. Some of the most famous and expensive sapphires in the world come from Kashmir (India), though the mines there have not been very active in recent decades. Many sapphires today are treated to enhance their colour or transparency, and synthetic sapphires are also present on the market.