TOURMALINE
The name tourmaline comes from the Singhalese words 'tura mali' - meaning something like 'mixed colour stone', referring to the wide colour spectrum of this gem, which outdoes that of all other precious stones. There are tourmalines from red to green and from blue to yellow. Single crystals often have two or more colours. There are tourmalines which change their colour when the light changes from daylight to artificial light, and some show the chatoyancy effect of a cat's eye.
Today, gem and specimen tourmaline is mined chiefly in Brazil and Africa, although some fine gem and specimen material has been produced in the US and Sri Lanka. The Empress Dowager Tz'u Hsi, the last Empress of China, loved pink tourmaline and bought large quantities for gemstones and carvings.
Almost every colour of tourmaline can be found in Brazil and in 1989, miners discovered a unique and brightly coloured variety of tourmaline in the state of Paraíba. The new type of tourmaline, which soon became known as paraiba tourmaline, came in unusually vivid blues and greens. The demand and excitement for this new material, which has fetched more than $50,000 per carat, earned more respect for the other colours of tourmaline.
Some tourmaline gems, especially pink to red coloured stones, are altered by irradiation to improve their colour. Irradiation is almost impossible to detect in tourmalines, and does not impact the value. Heavily-included tourmalines, such as rubellite and Brazilian paraiba are sometimes clarity enhanced, which must be disclosed to the buyer. A clarity-enhanced tourmaline (especially paraiba) is worth much less than a non-treated gem.