Black Star Sapphire : Star Sapphire is a wonderful gemstone. It is similar to normal Sapphire except for the fact that it has special inclusions that can be cut in a certain way to give the gemstone an asterism or star shape. Star Sapphires are only used for ornamental jewelry; however, it should be noted that Corundum, the mineral that Star Sapphire comes from is used for many industrial uses in its common form including abrasives.
22.27-Carat Rare GIA-Certified 12-Ray Star Sapphire from Burma,Gemstone : Natural 12-Ray Star Sapphire,Colour : Very Dark Blue,Clarity : Semi-Translucent,Star Sharpness : Very Clearly Visible 12-Ray Star,Grading : A (on a scale of A to E),Origin : Mogok (Burma),Mohs Hardness : 9 (On a Scale of 10),Treatments : None (Guaranteed Natural & Untreated)
Purple 12-ray star sapphire, 8.13 ct, 11.78 x 10.50 x 6.28 mm. Unlike this one, such stones often are glass-filled. For a brief report on the phenomenon, see “Twelve-rayed star sapphire of interest” by Garry DuToit, GIA Laboratory, Bangkok. (Photo: Jeff Scovil)