Chrysoprase is considered the most important gem in the chalcedony group. The name in greek means gold leek. the colouring agent for this gem is nickel. It is found worldwide but now belived to be worked out in Poland. Naerly always found in cabochon cut a few examples are founf faceted always opaque to translucent. It has a mohls hardness of 6.5-7 and a refractive index of 1.530-1.540.