Uncut emerald showing its natural hexagonal structure
Emerald (Be3Al2(SiO3)6) 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, although it is often made less so by inclusions, which all emeralds have to some degree. Beryl has a hardness of 7.5 on the 10 point Mohs scale of hardness. However, this Mohs rating can decrease, depending on the number and severity of inclusions in a particular stone.
Most emeralds are oiled as part of the post lapidary process. The amount of oil entering an emerald micro fissure is roughly equivalent to the size of a period in print. Emeralds come in many shades of green and bluish green. There is a wide spectrum of clarity, along with various numbers of inclusions. Most emeralds are highly included, so it is quite rare to find an emerald with only minor inclusions. Because of the usual inclusions, the toughness (resistance to breakage) is classified as generally poor.
Emeralds in antiquity were mined by the Egyptians and in Austria, as well as Swat in northern Pakistan.
A rare type of emerald known as a trapiche emerald is occasionally found in the mines of Colombia. A trapiche emerald exhibits a "star" pattern; it has ray like spokes of dark carbon impurities that give the emerald a six-pointed radial pattern. It is named for the trapiche, a grinding wheel used to process sugarcane in the region.
Cultural, historical/mythical and healing usage
Emerald is regarded as the traditional birthstone for May , as well as the traditional gemstone for the astrological signs of Taurus and Cancer.
Also used as energy balance, good lack talisman or amulet and healing stones.
In some cultures, the emerald is the traditional gift for the 55th wedding anniversary. It is also used as a 20th and 35th wedding anniversary stone.
Gachala Emerald (origin: Colombia)
Chalk Emerald (origin: Colombia)
Duke of Devonshire Emerald (origin: Colombia)