Golden star sapphire
Is a corundum variety that exhibit a fenomenal effect called asterism. A star,generally of siz rays,but rarely of four and 12 ( in case of gemination ) is seen when the strong beam of light heat the domed surface of the stone.
The cause of this effect in the golden star sapphire ,like in the black variety, is due to a combination of hematite platelets together with rutile.Is much rarer compared to the back type and big size are very expensive. The back side of the stone is unpolished.From Thailand.