Star sapphire is a rare variety of sapphire displaying asterism under specific lighting. Typically seen as a six rayed star that floats across the surface of the cabochon. The star is caused by tiny needle-like inclusions of rutile that intersect at different angles and reflect light.
Important deposits of fine star sapphires are today mined in Australia, Myanmar (Burma), Sri Lanka and Thailand. This particular variety of sapphire is often opaque, while top quality star sapphires might be slightly translucent, due to the rutile needles, star sapphires have a silky luster.
The rays should be uniform in strength and length, reaching from one side of the stone to the other. They should be straight and not fuzzy and move uniformly with the stone. Unsurprisingly, ancient legends describe this stone as being a potent talisman, providing security and protection.
Sapphire is the birthstone for September and the gem of the 5th and 45th anniversaries.
Sri Lanka, Madagascar, Burma and various other localities
9.0 on Mohs Scale
5th and 45th
1.762 to 1.770
0.008 to 0.010