Emerald is one of the most desirable gemstones, they are rich green variety of beryl.
Beryl provides some of nature's most beautiful gemstones. Although it is colorless in its pure form, it is perhaps best known for its colored varieties, which include aquamarine and emerald - indeed, its name comes from the Greek beryllos, meaning " green stone " . The colorless from of beryl is known as goshenite, and its clarity is such that it was used to make lenses for some of the earliest eyeglasses during the late Middle Ages.
where colors do occur in beryl, they are caused by minute chemical impurities, and this is sometimes reflected in the varieties' names. The green color of emerald, for example, is caused by traces of chromium. Morganite is colored pink, rose lilac, peach, orange, or pinkish yellow by the presence of manganese, and its crystals sometimes show color banding, with a sequence from blue near the base to nearly colorless in the centre, to peach or pink at the tip. it is almost always faceted, and stone with a yellow or orange ting are sometimes heat-treated to emphasize their pink tones. Manganese is also the coloring agent in the rare red beryl, sometimes called red emerald or scarlet emerald. The color in blue and green aquamarine (meaning "sea water"), and yellow to golden heliodor (from the Greek helios, meaning "sun"), result from traces of iron. Much greenish-blue aquamarine is heated to produce an intense blue color that has become popular in modern jewelry.
The name emerald derives from Greek smaragdos. It means "green stone" and, in ancient times, referred not only to emeralds but also prabebly to most green stones.
Emerald is found in igneous, metamorphic and sedimentary rocks. Most emeralds have numerous inclusions and internal flaws. For jewellery, the brittel gem is usually faceted in its signature emerald cut.This is a step cut which combines a rectangular shape with shortened corner facets, maximizing the emerald's distinctive green color and protecting it from external damage and internal stress.
Only the finest specimens are transparent. Often the emerald is clouded by inclusions. The physical properties, especially the density, refractive index and double refraction, as well as the pleochroism, vary according to source area. All emeralds are brittle and combined with internal stress, sensitive to pressure; care must be taken in heating them. They are resistant to all chemicals which are normally used in the household.
Deposits: Emeralds are formed by hydrothermal process associated with magma and also by metamorphism. Deposits are found in biotite schists, clay shales, in lime-stones, with pegmatites.
Significant deposits are in Colombia, especially the "Muzo" mine. Emerald deposits were discovered in 1830 in Russia in the Urals north of Yekaterinburg, but the yield has fluctuated widely over the years. Further emerald deposits are in Afghanistan, Australia, Ghana, India, Madagascar, Malavi, Mozambique, Namibia, Nigeria, Pakistan, Zambia, Tanzania and the United States.
Famous Emeralds: there are many well-known large emeralds, as valuable and famous as diamonds and rubies. Some beautiful specimens of several hundred carats are kept by the British Museum of Natural History in London, by the American Museum of Natural History in New York, in the treasury of Russia, in the state treasury of IRAN and in the treasury room in Topkapi Palace, Istanbul, Turkey. In the Viennese treasury is a vase, 12 cm high and weighing 2205 ct, cut from a single emerald crystal
chemical name Beryllium aluminium silicate
colors colorless, red, blue, green,yellow
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