Sunday, May 1, 2011

Emeralds are the Gemstone of the Week

This week, the gemstone of the week is also the birthstone for May, the beautiful, enchanting, lush green Emerald. The name comes from the French word “esmaraude” which in turn, goes back via Latin to the Greek root “smaragdos” which simply means “green gemstone”.

Emerald is the most precious and expensive member of the Beryl family of gemstones. It is classified as one of the four traditional gemstones along with diamonds, sapphires and rubies. Along with being the birthstone for May, it is the gemstone for the 20th and 35th anniversary.

Clarity is important for Emeralds, but inclusions or flaws, are much more tolerated with this stone than they are with other gems. They help assure the buyer that they are getting a genuine Emerald. This gem has a hardness on the Moh scale of 7.5-8. Inclusions do make this stone brittle and more difficult to cut. Because of the enhancements to Emeralds, which I will cover a couple of paragraphs down, these stones should not be cleaned using ultrasonic jewelry cleaners.

Color is the main consideration when grading and pricing Emeralds. By definition, Emerald is a medium or darker green to bluish green. The most valuable stone is slightly bluish green with a medium dark tone with strong to vivid color saturation. Emerald color comes from chromium, vanadium or a combination of both. Emerald is a beryllium aluminum silicate.

Emeralds are often enhanced by oiling.This is done by placing the stone in a vacuum chamber with heated oil, and sometimes resins. Not only does this improve the appearance of the stone, but also helps to fill in the inclusions it has. Steam cleaning, using solvents or ultrasonic jewelry cleaners will remove these oils and change the appearance of the stone. Clean an Emerald with a soft, dry cloth.

Almost all Emerald mining is done from host rocks where the Emerald has grown into small veins or on the walls of cavaties. Columbia is the world center for Emerald mining. Northwest of Bogota is a mine called the Muzo mine which produces deep green, fine quality stones. To the Northeast of Bogota is the mine called Chivor which also has high quality deposits of Emeralds. Brazil also has Emerald mines which produce a lighter color green gem. There is also a mine in Brazil which produces a rare form of Emerald known as a Trapiche Emerald. This stone is characterized by star shaped rays that come from the center of the stone in a hexagonal pattern. This pattern is caused by black carbon impurities that form in a star pattern. Emeralds are also found in Transvaal, Zimbabwe, Russia, Australia, Ghana, India, Madagascar, Malawi, Mozambique, Namibia, Nigeria, Pakistan, Tanzania, and Zambia. Not all of these deposits produce high quality stones, some are suitable only for beads and cabachons. They are also found in the U.S. in North Carolina which has made Emerald the official state gemstone.

Emeralds have been mined since around 1500 B.C.. Many museums have incredible collections and there have been many famous Emeralds over time. One of the most famous and legendary Emeralds is the Mogul Emerald which dates from 1695. It weighs in at 217.80 carats and is 10cm high. One side is inscribed with prayer texts, the other side has floral engravings. In 2001, Christies auctioned this off for $2.2 million dollars to an unidentified buyer. The Viennese Treasury contains an Emerald vase that is 4.5 inches high, has a carat weight of 2205 and was carved from a single Emerald crystal. One of the largest Columbian Emerald crystals is on display at the New York Museum of Natural History. It is called Patricia and has a carat weight of 632. The Bank of Bogota has a collection of five Emerald crystals with carat weights that range from 220 to 1796. Other countries also have incredible, historic Emeralds in their palaces and treasuries, including Iran, India and Turkey.

Stories and legends have sprung up around Emeralds for centuries. It is believed that when worn, it will protect from epileptic seizures, give the wearer wisdom, faith and success in love. It is also believed it will drive away evil spirits, aid in spinal ailments, mental illness and neurological ailments and as an antidote for poison.

Synthetic Emeralds have been on the market for several years. They are considerably lower priced than genuine Emeralds. Watch out for these names, they are often synthetic-Biron, Chathan, Gilson, Kimberly, Lennix, Regency, and Zerfass. Some of the names given to green dyed glass and passed off as genuine are Broughton, Endura, Ferrer's, Medina, Mt. St. Helens, and Spanish Emerald. Sometimes, other stones are sold as Emeralds. Green Flourite has been called African and Bohemian Emerald, South African and Transvaal Emerald. Dyed quartz, prehnite, peridot and green sapphires are passed off as Emeralds also. Another practice is the selling of Emerald doublets. A doublet is created when two lesser quality stones are adhered together with a colored paste and passed off as a single stone. Since a good quality Emerald is an investment, be sure to buy your stone from a reputable dealer and do some research so you know what you are buying.
 The pictures are 1. The front of the Mongul Emerald. 2. The Patricia Emerald 3. The Emerald Vase from the Viennese Treasury.

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