Tourmaline (from the Sinhalese word: Thurmali or Thoramalli, meaning different mixed colour) is a crystal boron silicate mineral compounded with elements such as aluminium, iron, magnesium, sodium, lithium or potassium.
Tourmaline is classified as a semi-precious stone and the gemstone comes in a variety of colours across the spectrum. In bi-colour, tri-colour, parti-colour, concentric colours. Those with predominantly blue shades, referred to as "indicolites" (from indigo) and pink and red hues, referred to as "rubellites" (from ruby) are prized and command the highest prices. Usually iron-rich tourmalines are black to bluish-black to deep brown, while magnesium-rich varieties are brown to yellow, and lithium-rich tourmalines are almost any colour: blue, red, green, red, yellow, pink, etc. It is rarely colourless. Bi-coloured and multicoloured crystals are common and some forms are dichroic in that they change colour when viewed from different directions. The "watermelon" tourmaline is either green at one end and pink at the other or green on the outside and pink on the inside.
Paraiba Tourmaline is an intense violetish blue, greenish blue, or blue tourmaline from the state of Paraiba, Brasil. A large cut tourmanline from Paraiba, measuring 36.44 x 33.75 x 21.85 mm and weighing 191.87 carats was included in the Guiness Book of World Records. The large natural gem is a bluish-green in colour. The flawless oval shaped cut stone was presented in Montreal, Canada in 2009. Gem and specimen tourmaline is mined chiefly in Brazil and Africa. Brightly coloured Sri Lankan gem tourmalines were bought to Europe in great quantities by the Dutch East India Company to satisfy a demand for curiosities and gems.