The 'Star ruby' is a rare variety of ruby that exhibits an asterism; a six-rayed star that shimmers over the surface of the stone when the light is moved. The star effect is owed to aligned needle-like rutile inclusions. It is the rutile which is responsible for its silky shine.
Traditionally, star rubies were worn by knights in the battlefields to protect themselves from their enemies. Local tales in Karnataka (India) say that if it is worn as a visible pendant or as a headgear then anyone who faces you as an enemy looses half their valour.