TOURMALINE
Tourmaline is a group of boron-rich silicate minerals known for its exceptional range of colours, which include green, blue, red, pink, yellow, brown, and black. They can also be colourless or display two or more colours within a single crystal. Among the species in the tourmaline group, most gem-quality material belongs to elbaite, valued for its variety of colours and crystal quality. First identified on the island of Elba, Italy, in 1913, elbaite is now found in many parts of the world. Other important tourmaline species include schorl, dravite and liddicoatite.

Schorl, commonly known as black tourmaline, is a sodium-iron tourmaline. It was known in Europe before the discovery and classification of coloured tourmalines. Its name comes from the village of Schorl, now Zschorlau, in Saxony, Germany, where it was mined alongside cassiterite before 1400. It was particularly popular during the Victorian era.

Dravite, or brown tourmaline, is a sodium-magnesium member of the group. It was first reported in the Drava River region of present-day Slovenia in 1884, where its name originated. Notable specimens come from Yinnietharra in Australia, with other deposits in Brazil, Mexico and Canada. Liddicoatite, named after gemologist Richard T Liddicoat, is a calcium-rich lithium tourmaline known for its complex colour zoning. It can display combinations of red, purple, green and yellow, often forming distinctive triangular patterns when cut as polished slices. It is particularly associated with the pegmatites of the Anjanabonoina region of central Madagascar and is also found in countries such as Brazil, Russia, Vietnam, Tanzania, the United States, and the Czech Republic.

History of Tourmaline
Tourmaline has a long history of being mistaken for other gemstones because of its wide range of colours. One of the earliest recorded encounters dates to 1554, when Francisco Spinoza’s expedition in Brazil encountered a green crystal that was believed to be an emerald. Tourmaline from Sri Lanka, then known as Ceylon, was later brought to Europe by Dutch merchants. Its name is thought to derive from the Sinhalese toramalli, meaning “stone with mixed colours”, a term used for the multi-coloured stones found in Ceylon’s gem gravels.

Tourmaline became particularly noted for an unusual property. When heated, it could attract small particles such as ash and then repel them. The Dutch called it aschentrekker, or “ash drawer”. This phenomenon, now known as pyroelectricity, helped distinguish tourmaline from other gemstones and contributed to its scientific interest. It was only in the 19th century, with the development of modern mineralogy, that tourmaline was recognised as a distinct mineral rather than being misidentified as ruby, sapphire or emerald.

In the late 19th century, tourmaline gained prominence in the United States, particularly after deposits were found in Maine and California. The renowned gemmologist for Tiffany & Co., George F Kunz, played an important role in promoting American tourmaline. California’s pink and red tourmalines subsequently found a major market in China, where Empress Dowager Cixi was particularly fond of the stones and had them carved into snuff bottles and jewellery. This trade was so significant that the American tourmaline market declined sharply after the fall of the Qing dynasty in 1912.

The discovery of new deposits, particularly in Brazil during the 20th century, expanded the range of tourmaline available to the gem market. The discovery of intensely coloured Paraíba tourmaline in Brazil in the late 1980s brought renewed attention to the gemstone, particularly for its vivid blue, green and violet hues. Although first discovered in Brazil, similar copper-bearing tourmalines are also now found in Mozambique and Nigeria.

Colours and varieties of Tourmaline
Tourmaline is distinguished by one of the widest colour ranges among gemstones.
- Red and pink tourmaline is commonly known as rubellite, while blue to bluish-green material is often called indicolite.
- Green tourmaline is sometimes referred to as verdelite, while colourless tourmaline is known as achroite.
- Particularly vivid blue and green tourmalines that acquire their colour due to the presence of copper are known in the trade as Paraíba tourmaline.
- The presence of manganese in addition to copper results in more violet hues.
- Some crystals also show distinct colour zoning, most famously the green-and-pink combination known as watermelon tourmaline.

Characteristics of Tourmaline
Tourmaline has a vitreous lustre and a hardness of 7 to 7.5 on the Mohs scale, making it well suited to jewellery. Its wide range of colours is influenced by its chemical composition, with elements such as iron, manganese, chromium, vanadium and copper contributing to different hues. Copper, often together with manganese, is responsible for the vivid blue, green and violet colours characteristic of Paraíba tourmaline.

Tourmaline can also show different shades when viewed from different directions, a property known as pleochroism. Some stones contain fine, tube-like inclusions that create a cat’s-eye effect when cut as cabochons. Its exceptional range of colours, colour zoning and occasional optical effects make tourmaline a particularly versatile gemstone for jewellery.