A big family of minerals, often confused with many other opaque stones. Of the few that are gem-grade, the yellow-green bowenite can be mistaken for jade; "verd antique" can be taken for a dark green marble; williamsite, which is dark green with black spots, is the only easily recognizable one. However, the varieties of serpentine all have a much lower rating on the Mohs hardness scale than the more valuable stones they are passed off as; the best test is to see how easily the stone can be scratched. While the mottled colors from which it gets the name are pretty, serpentine is usually too soft to be used for jewelry.