Black Star Sapphire
Although many default to the color blue when "sapphire" is mentioned, it is not only blue. The term "sapphire" describes any color variety of the mineral corundum that is not red, being that red corundum is defined as ruby.
Asterism, a star-effect, may appear on the surface of a piece of properly cut cabochon corundum. The gem is then classified as a "star sapphire" (if not red) or "star ruby" (if red). Major sapphire mines are found in Sri Lanka, Tanzania, Madagascar, Thailand, Myanmar, and Australia.