Ruby abd sapphire belong to the mineral family called corundum. Chemically they are both aluminium oxide in a crystalline form that was made deep underground into clear and beautiful gemnstones under high pressure and heat. Impurities within the crystals give it the attractive, glowing colours. Good specimens of these gems are perhaps almost as valuable as diamonds. All colours of corundum except red are known as sapphires. The colorless variety is called white sapphire and was once a cheap substitute for diamonds. Yellow, purple, pink, green or white sapphires are called "facy" by the trade. Red corundum is now termed as ruby but there was a controversy some years ago on the difference between ruby and red or pink sapphire. In 1991, the International Coloured Gemstone Association ruled that even the lighter shades of red corundum should be termed ruby.
Sapphires and rubies are found all over the world and are mined in Australia, Brazil, Cambodia, China, Kenya, Nigeria, Russia, Sri Lanka, Tanzania, USA, and Zambia, but the gemstones from India, Myanmar, Sri Lanka, Thailand and other countries in the far east were and still are renowned for their pure, rich color and quality. Specially Sri Lanka produces the world's best quality blue sapphires. Good quality stones have been found in Sri Lanka, all over india, from Tamil Nadu in the south to Kashmir in the North. Blue sapphires from the very inaccessible mines of the Zanskar valley in Kashmir are produces good quality gemstones than other parts in the India. Discovered in 1880 after a huge rock slide, they have a pure intence blue color, with a slight measure of silk or milkiness. The oldest sapphire mines were in Sri Lanka and gems found there are light to rich blue in colors. Cornflower blue color sapphires are only found in Sri Lanka, and are very high in price. Sapphires from Madagascar are of high quality with some exceptional yellow and pink stones. Brazil has unearthed some good blue to purple and pink stones recently.
Sapphires from Sri Lanka is known as "Ceylon Sapphires".