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All of a sudden we found out that in the Britain culture one of the May birthstones is chrysoprase. Chrysoprase, chrysophrase or chrysoprasus is a gemstone variety of chalcedony that contains small quantities of nickel. The word chrysoprase comes from the Greek CHRYSOS, meaning "gold" and PRASINON, meaning 'green'. Its color is normally apple-green, but varies to deep green.

Chrysoprase is cryptocrystalline (like agate, carnelian, and onyx), which means that it is composed of crystals so fine that they cannot be seen as distinct particles under normal magnification. This sets it apart from rock crystal (clear quartz), amethyst, citrine, and the other varieties of crystalline quartz which are basically transparent. Unlike many non-transparent minerals, it is the color of chrysoprase, rather than any pattern of markings, that makes it desirable.

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Because of its attractive color chrysoprase has been used as a gemstone since ancient times. Possibly the most famous source of chrysoprase is the region of Silesia in Poland. This source has been used since medieval times and some of its gems were used to make jewelry for kings, most notably King Frederick II of Prussia. King Frederick even discovered a vein of chrysoprase there that was three miles long! Since the source in Poland has been just about exhausted the market has turned to other sources.

Today the best known sources of chrysoprase are Queensland, Western Australia, Germany, Russia, Arizona, California, and Brazil. The chrysoprase deposit in Szklary, Lower Silesia, Poland, was probably the biggest European chrysoprase occurrence and possibly also the biggest in the world.