Emerald – The Most Valuable Member of the Beryl Family
At one time all green gemstones were refered to as emeralds. When we were able to determine that not all green stones were emeralds, we also discovered that some of the Egyptian Queen Cleopatra’s Emeralds were infact another less expensive green gemstone called Peridot.
This is the 75ct Hooker Emerald Brooch. This brooch is found at the Gem and Mineral Collection of the Smithsonian’s National Museum of Natural History.
After determining that not all green stones were emerald gemmologists were then able to determine that emerald has the same chemical composition as Aquamarine (light blue or light green), Heliodor (yellow/golden), Goshenite (colourless), Green Beryl lLight green), Bixbite (red) and Maxixe (dark blue that fades in daylight). These are all varieties of beryl.
They are all Beryllium Aluminum Sillicate [Be3Al2(SiO3)6]. It is the trace impurities of chemicals that cause the different colours. Emeralds have trace elements of chromium, aquamarine is coloured by iron. If you have a beryl that is a light green, but not the deep green tone of emerald, then it is called green beryl and it may be coloured mainly by iron. The GIA now identifies beryl coloured green by vanadium as emerald, Gem-A does not.
Emeralds can be found in Afghanistan, Brazil, Colombia, India, Packistan, South Africa, former USSR, Zambia, Zimbabwe and the USA. The best ones come from Colombia.
Most emeralds on the market today are treated to increase their durability and to enhance their colour. An emerald at a very good price may actually be a synthetic, this means it has the same chemical composition and crystal structure as the natural emerald, but it was grown in a laboratory. Don’t go by the rule that if it has inclusions then it is natural, many synthetic methods leave tell-tale inclusions in the synthetic stone. A good gemmologist can determine if it was created by the hydrothermal method or the flux synthetic method.
Be very careful when purchasing an emerald! Maybe it is green beryl, peridot, an imitation emerald or a synthetic emerald. If you can afford a natural emerald you should find out what treatments has it undergone. Time to make friends with a gemmologist.
Pliny the Elder (AD23-AD79) reported in his Historia Naturalis that, in olden days, beryls were used as eye glasses. It is said that the Emporer Nero watched galiator fights through an emerald. I guess he could afford emeralds without many inclusions!
Your Input (Join our poll or scroll down and leave a comment) – Emerald is winning the poll!
I plan to introduce different gemstones alphabetically. I will start with “A” (Ammolite) and see where it leads me. Leave a comment and let me know if you have a favourite gemstone that starts with the letter “F”. Take the poll! Can you name a reference to a gemstone in a song, movie or book?
Posted on July 14, 2011, in Individual Gemstones and tagged beryl, Cleopatra, Emerald, flux, GEM-A, gemmologist, gemmology, gemologist, gemology, GIA, gladiator, glasses, historia naturalis, hooker emerald, hydrothermal, morganite, peridot, pliny, smithsonian, synthetic. Bookmark the permalink. Leave a comment.