Available in all the colours of the rainbow, Tourmaline also has a very complex mineral composition, which is the main reason behind their rich colour composition. Gemstones from Sri Lanka belonging to the Tourmaline species differ from yellowish-green to bright green.
One of the most important gem Tourmalines found in Sri Lanka are mixtures of Dravite and Uvite. Often brown, yellowish-brown, reddish-brown, or nearly black in colour, these species contain traces of vanadium, chromium, or both. When present in the right concentrations, these impurities produce rich green hues similar to tsavorite garnet.
While Uvite is rich in calcium, magnesium, and aluminium and Dravite is rich in sodium, magnesium, and aluminium; both forms within limestone that have been altered by heat and pressure and are fondly known as Savanna Tourmaline by gem dealers and merchants.
Most of the brown and yellowish-brown varieties are located mainly around Uva, Ratnapura and Tissamaharama regions in Sri Lanka while Lunugala, Bibile, Passara, Nilgala region, Horana, Matugama, Pelawatte, Morawaka, Deniyaya, Rakwana areas in the country also produce impressive specimens.