Star stones of the corundum family are either star sapphires or rubies. When light falls on these stones, a star effect is visible (known as asterism).
Sri Lanka is the best known source for star sapphires and star rubies. Star sapphires range in colour from grey to bluish-grey and from medium blue to medium dark blue. The very slightly purplish medium dark blue is the best colour grade for star sapphires. Star rubies range from light pink-red to purple-red through deep purple-red. The intense red star rubies are extremely rare. A good quality star stone should have a high degree of transparency and a well defined star with no weak or missing rays. It should be reasonably clean and in the face-up position, no distracting inclusions or cracks should be seen. There should be no excess weight at the bottom of the stone.
Star sapphires and rubies are hard stones (9 on the Moh?s scale), which can take a high degree of polish and retain the shinefor a long time.
The special optical phenomenon of a well-defined six-ray star is a fascinating sight. The wearable qualities of the star stones make them suitable for men’s rings.