A mineral of which the colour ranges, owing to the presence of varying quantities of iron, from yellow to pale green to dark bottle-green, sometimes having more than one shade in the same crystal.
Some specimens that have inclusions show chatoyancy and are cut en cabochon, and some show asterism with a four-pointed star. Small crystals used for gemstones are transparent and are sometimes step cut. Varieties include alalite, baikalite, chromdiopside, and violan(e).
From: An Illustrated Dictionary of Jewelry, autor: Harold Newman, publishers: Thames and Hudson