For other things of this name, see Emerald (disambiguation).
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 by weight is the most valuable gemstone in the world, often made more so by inclusions. Beryl has a hardness of 8 on the 10 point Mohs scale of hardness. Emerald is the birthstone for May as well as the traditional gift for the 55th wedding anniversary.
Emerald is a rare and valuable gemstone which naturally provided the incentive for developing synthetic emeralds. Both hydrothermal and flux-growth synthetics have been produced and a method has been developed for producing an emerald overgrowth on colorless beryl. Synthetic emeralds fluoresce a dull red with long wave UV whereas most natural specimens do not. Also both the densities and refractive indices of synthetics are slightly lower. Wispy inclusions are common in flux-grown synthetic emeralds.
See also: List of minerals