Transparent to translucent natural or synthetic variety of corundum that is highly prized as a gemstone. Its colour is due mainly to the presence of small amounts of iron and titanium and normally ranges from very pale blue to deep indigo. Colourless, gray, yellow, pale pink, orange, green, violet, and brown varieties also are known as sapphire; red varieties are called ruby. Synthetic sapphire has been produced commercially since 1902. Much is used in jewelry, but most is used in the manufacture of jewel bearings, gauges, dies, and other specialized components; some also is used as a high-grade abrasive. It is found in Sri Lanka, Myanmar, India, and Montana in the U.S.