Diopside, specifically chrome diopside, is a chromium-rich, transparent to translucent variety of gemstone-quality calcium magnesium silicate. It is one of the rarer varieties of diopside and belongs to the pyroxene family of minerals.
Diopside is most famous for its attractive forest-green colour, but depending on the impurities and colouring agents, diopside gemstones can actually occur in a variety of different colours, including common black to near-black, rare violet-blue and light yellowish-green to medium dark-green. Chrome diopside is an officially recognized variety of diopside and one of the newest gems on the market today. Even though it's considered relatively new, it very quickly made its way into the mainstream gem trade and became one of the most popular green gemstones of today. Despite the widespread belief that green gemstones are common, naturally occurring green gemstones are actually quite rare.