Chrysoprase the most valued variety of chalcedony means “golden apple” in Greek. A semitransparent to translucent apple green stone, its finest color is the light to medium yellowish green of the fruit. In poor quality material the stone may be opaque. The highest quality material is of even color, without flaws, fractures, inclusions, cavities or other imperfections. Most green stones derive their color from chromium or vanadium, where natural chrysoprase owes its color to nickel silicate impurities. It is rare but chrysoprase can be colored by chromium rather than nickel producing a green to bluish green color. In some chrysoprase the color may fade when heated or exposed to sunlight.
As the most prized of all fine chalcedonies, this sensational stone has been used for centuries. It is a gem that is easily worked with and takes a fine polish and is principally fashioned into cabochons, beads, bangles, carved into jewelry or other ornamental objects. Both the Greeks and Romans used chrysoprase as a decorative stone. “King Frederick the Great of Prussia, who reigned from 1740 to 1786, decorated his palace with furniture and art objects inlaid with chrysoprase.”
Although the color is alluring, chrysoprase is not commonly known today because of its limited availability. Revived interest in chrysoprase came in 1965, with the discovery of the gem in Queensland, Australia, the area has since been producing superior quality chyrsoprase for commercial use. The finest Queensland gem material ranging from apple green to a saturated medium to dark green can resemble fine jade. Brazil produces a chrysoprase often found in an olive green color. Other localities include California, India, the Ural in Russia, and Austria.
Dealers created treated alternatives, to compensate for the rarity of the stone before the Queensland find made chrysoprase more available. These treated alternatives are often sold as green agate or green onyx, that are grayish chalcedonies that have been soaked in a mixture of water, acid, and chromium, or nickel compounds, then heated and dried. The hues that are created from treating green chalcedony are often a green to bluish green color, rather the intense green of the naturally colored gem material.
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