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.
- malachite (the original "true" emerald)
aquamarine, another variety of beryl)
- prase (a leak-
- chrysoprase (a type of chalcedony, the color ranges from pale to apple green)
- jasper (the term iaspis originally referred to several spotted green stones, which may have included serpentine and nephrite jade)
- Cariadoc's "On gemstones"
- Walter Schumann, Gemstones of the World, New York, (rev) 1997