Emerald

From Cunnan

The emerald is a variety of the mineral beryl, colored green by trace amounts of chromium and sometimes iron. It is highly prized as a gemstone and ounce for ounce is the most valuable gemstone in the world, often made more so by inclusions.

In ancient times and throughout the early Middle Ages, the term emerald could mean any green gemstone. Pliny the Elder mentions 12 varieties of emerald; among them are:

• malachite (the original "true" emerald)
• emerald (described above—Pliny also recognised the kinship between emerald and aquamarine, another variety of beryl)
• prase (a leak-green variety of quartz—since modern times it has also been known as aventurine quartz)
• chrysoprase (a type of chalcedony, the color ranges from pale to apple green)
• peridot (the "evening emerald"—originally known as topaz, the term peridot dates from the time of the Crusades)
• jasper (the term iaspis originally referred to several spotted green stones, which may have included serpentine and nephrite jade)

See also:

• Emerald according to Maplet's A Greene Forest

References:

• Cariadoc's "On gemstones"
• Walter Schumann, Gemstones of the World, New York, (rev) 1997