A star sapphire is a type of sapphire that exhibits a starlike phenomenon known as asterism; blue stones are known as “star sapphire .
Star sapphires contain intersecting needle-like inclusions following the underlying crystal structure that causes the appearance of a six-rayed “star”-shaped pattern when viewed with a single overhead light source. The inclusion is often the mineral rutile, a mineral composed primarily of titanium dioxide
|Refractive Index||1.762 to 1.770|
|Birefringence||0.008 to 0.010|