Chrysoprase is a gemstone variety of chalcedony that contains small amounts of nickel and is the second most valuable variety of Chalcedony, gem silica being the first. Chrysoprase occurs in a range of green colors. Its glowing color varies from the more common apple green to darker shades of green. The abundance of nickel determines the strength of the green color. With a 6-7 hardness on the Mohs scale it is hard and will take a beautiful polish.