A to Z of Gemstones: T: Tourmaline


Gemstone family: Tourmaline

Crystal System: Trigonal

Moh's scale of hardness: 7-7.5

Lustre: Vitreous

Birthstone: October

About: Tourmaline’s name derives from the Sinhalese word 'toromalli' which means 'mixed gems'. Tourmalines are found in a wide range of colours; pink, green, blue, orange, yellow, brown, black, and colourless.  Bi-coloured Tourmalines are also common and stones which are coloured pink to green are known as watermelon tourmaline.  Tourmalines can also display cat's eye chatoyancy, which is caused by parallel fibres running through the stone.

Origin: Tourmaline is found in many countries including Madagascar, Brazil, USA, Burma, Sri Lanka, Botswana and Namibia, Zambia and Afghanistan.

Use in jewellery: Tourmaline is suitable for most types of jewellery and is cut into faceted stones, cabochons as well as beads and carvings.

Treatments, synthetics and imitations:  Rarely tourmalines are heated to enhance their colour.

Famous examples: A large cut tourmaline from Paraiba, measuring 36.44 x 33.75 x 21.85 mm and weighing 191.87 carats, was included in the Guinness World Records in 2009.  The large natural gem, owned by Billionaire Business Enterprises, is a bluish-green colour, flawless oval cut stone.