Diopside is a vitreous gemstone, with colours that include green to brown, white and black. Usually transparent to translucent, the black star variety of diopside is opaque and displays a 4 pointed star or asterism.
Another variety is Chrome Diopside. A green gemstone that can sometimes display a cat's eye effect or chatoyancy.
Most Chrome Diopside originates from Russia, where as Black Star Diopside comes from India.