Synthetic Ruby

The ruby is one of the most precious gemstones and has long been revered for its brilliant red colour. Rubies are made of the mineral corundum, which is aluminium oxide. Pure corundum is clear, but a trace amount of chromium in rubies is enough to give them their characteristic red colour. All other types of corundum minerals are called sapphires and come in a variety of colours. Naturally occurring rubies can be mined in many places around the world, but they are predominantly found in Asia: the Mogok Valley in Burma was for a long time the world’s main source of rubies and has yielded some of the finest rubies ever discovered. This ruby, however, is synthetic. Over the last two centuries many successful attempts have been made to synthesise rubies, which mainly involved flaming aluminium oxide and chromium in the presence of various chemicals. Such synthetic rubies have technological as well as aesthetic applications - ruby lasers, invented in the USA in the 1960s, make use of the ruby’s optical properties by exciting the crystal and harnessing its sharp red emission.