A Lindy star sapphire is a synthetic star which is essentially painted on a stone. It was manufactured by the Linde division of the Union Carbide Corporation between the 1950s and 1970s. Production stopped in 1974 due to increased overseas competition from Southeast Asia.
Star sapphires are popular because they exhibit a phenomenon known as asterism. In asterism, a silky star-like effect occurs due to arranged inclusions within the stone, creating a beautiful shape. On a Lindy star sapphire, the star is basically painted onto the stone artificially. An average customer may not be able to tell the difference. However, an experienced purchaser should be able to tell the difference between a synthetic and genuine star.
Jack Burdick is credited as the co-inventor of the Lindy star sapphire. In 1947 Burdick attempted to improve the blue sapphire by producing a more uniformly colored material. His company experimented with various methods, including heating the stones at high temperatures for several days without iron. The accidental result was a star. Although Burdick noticed that the new stones looked different, it wasn't until he went out to smoke a cigarette that he saw the sunlight hit the stones and the stars shining brightly.