Sapphire

Sapphire is an aluminum oxide. Its color varies from very light to dark blue to Violette-blue, bluish-green, yellow, slightly reddish-orange, brown, nearly opaque black, colorless, pink, violet and the pinkish-orange padparadscha (lotus flower).

Varieties 
Coloured varieties, star sapphire, alexandrite-like sapphire. 

Sources 
Sri Lanka, Kashmir (India), Burma, Thailand, Australia, Tanzania, Kenya, Montana, Madagascar 

Toughness 
Excellent, except in laminated or fractured stones. 

Precautions 
Sapphires may fade if heated 

Treatments 
Sapphires can be x-rayed to intensify their color. Natural sapphires undergo heat and diffusion treatments in Thailand. With the first method, sapphires with latent chemical components for good color are "ripened" to a desirable color through heating. In diffusion treatment, sapphires that lack the components for good color are placed in a bath of coloring oxides that penetrate the outer layers of the stone. Treatment of blue stones is permanent. 

History 
According to an ancient Persian legend, the earth rested on a great sapphire whose reflection was seen in the sky. The stone also appears in the Promethean legend. Prometheus was chained to a rock by Zeus for having stolen fire from the gods. After being rescued by Hercules, a link of the chain remained on his finger, and attached to it was a piece of rock. Zeus agreed to grant Prometheus his freedom if he wore the link as a reminder of his sin. Later a ring set with a sapphire replaced the link and stone. Sapphire symbolizes truth, sincerity and constancy. It was believed to protect the wearer against capture by an enemy, and to win the favor of princesses. It also protected against poison. It was said that if a poisonous snake were put in a vessel with a sapphire, the rays from the gem would kill it. The name sapphire originally comes from Sanskrit. It became sapphires in Greek, meaning blue. Before the value of sapphire was known to them, villages in the Zanzibar mountains of Kashmir (India) used the gem as a flint to start fires. 

Cuts & Uses 
Faceted and en cabochon, usually mixed cut, beads, carved (poor quality). Synthetic sapphire is used in watches, precision instruments and electronic equipment.