Chrysoprase is the most valued of all chalcedonies. Alexander the Great wore one on his girdle during all his battles.
It was a particular favorite of Frederick The Great of Prussia, who loved its bright green color. Unlike most other green stones, which owe their color to chromium or vanadium, chrysoprase derives its color from nickel.
The term chrysoprase should be reserved for the natural material. It should not be applied to the green dyed chalcedony that is often sold as « green onyx ».