Opal Stone – Natural, Tumbled, Gray

This gray opal shows a wide range of hues in its play of color. "Precious opal (Bulldog Shale, Lower Cretaceous; Coober Pedy Opal Field, South Australia) 1," photo by James St. John. Licensed under CC By 2.0.

Article: Eight Opal Types Explained

Credit: James St. John