The month of October has two beautiful gemstones – tourmalines and opals. I thought I would write about them separately. I am always surprised that we don’t see more tourmalines used in jewellery. The range of colours is stunning – from greens, pinks, yellows, browns, blues, black, and lilac, to the red version called rubellite. The paraiba, originally found in Brazil but now also from Nigeria, and Mozambique, is a vivid blue to green stone. There are also the lovely part-coloured ones, like the watermelon tourmaline which is green on the outside and pink in the middle. It is a hard stone, 7 to 7.5 on Mohs’ scale so good for jewellery..
Used as a gemstone since antiquity, tourmaline was not identified as a separate gemstone family until the early 1700s. Before then, it was assumed that if a stone was green, it was an emerald, if blue, a sapphire, red a ruby and pink an amethyst, pink sapphire or topaz.
Heat and irradiation are the main treatment for tourmalines, sometimes both, aimed at improving and brightening colour. The treatments are considered stable. There have not been synthetics produced.