Star sapphire

Star Sapphire is a very rare form of sapphire that exhibits asterism, a reflective optical effect that highlights a white six-pointed star on the surface of cabochon-cut stones. Star sapphires are more opaque than regular gem-quality sapphires. They are often used in making and decorating devices and objects to ward off hostile magic. A typical specimen has a base value of 1,000 gp or 5000gp.