Emerald Gemstone Varieties
by Madhubanti Rudra
Emeralds differ in shine and color depending upon the locale of its mine. It is only the Columbian emerald that has the characteristic vivid, slightly bluish green tones of medium-to-medium dark color. Deposits of the stone are also found in other parts of the world such as in Zambia, Zimbabwe, Madagascar and Nigeria. However Columbia and Brazil are the leading producers of emerald today.
Summary: Green is life. Green is happiness. So is emerald. For ages it has been a regal choice. But the common men are often confused at the time of buying this magnificent gemstone. Knowledge about the emerald classification will help you to sail through the bargaining process for the right stone. So read on the article to learn about different types of emeralds
“He who possesses it shall enjoy special protection of God”-reads a talismanic Mughal emerald. This birthstone of the month of May has been the passion of Cleopatra and love of the Mughals. Along with ruby, diamond, and sapphire, emerald is an important member of the big “awesome foursome” and has long been attributed healing and mystic prowess. Being associated with the planet Mercury, emerald is traditionally believed to cure diseases like forgetfulness, epilepsy, stammering and even insanity. Attributing mystic qualities to this gem, it is said that this piece of stone brings foresight and wisdom to the possessor.
Emerald (Be3Al2Si6O18) is the grass-green type of Beryl. Mostly it occurs in mica schists of metamorphic-hydrothermal origin. The formation of emerald involves a natural process known as exometamorphism. During this phenomenon if the basic rock contains the elements chromium or vanadium small quantity of it might get incorporated in the structure of beryl. This gives the rock its gemlike green color. Varying amount of iron also alters the color of the rock. It has a hardness of 7.5-8 and a refractive index of 1.57-1.59. However it is not a gem recommended for ‘everyday’ use since it falls in the category of soft stone. The real worth of the gem rests in its green dazzle and variations in shades. They range in color from slightly yellowish green to darker bluish green. The cut of the stone is also significant. Although faceted emerald can have round, pear, oval shapes the emerald cut, that is, octagonal shape is most preferred. Inclusions are almost an accepted fact in emeralds.
Emeralds differ in shine and color depending upon the locale of its mine. It is only the Columbian emerald that has the characteristic vivid, slightly bluish green tones of medium-to-medium dark color. Deposits of the stone are also found in other parts of the world such as in Zambia, Zimbabwe, Madagascar and Nigeria. However Columbia and Brazil are the leading producers of emerald today. The mines of Egypt, which supplied emeralds to Cleopatra, are not much into production today. Among the foremost consumers of emerald are USA and Japan who buy 75% of the world’s cut emerald.
COLUMBIAN EMERALD GEMSTONE
Columbia is the foremost producer of emeralds. Both in terms of quantity and in terms of quality Columbian emeralds lead the world. The transparency, crystallization and fire identify a Columbian emerald. It is the deep green shade of Columbian emerald that is taken as standard.
History depicts that when the Spaniards conquered America the Egyptian mines were no longer producing emeralds. The conquest brought the Spaniards into a land laden with one of the world’s most precious stones. It is primarily the rich colour and proverbial quality of emerald from the Andes mountain ranges that has distinguishes Columbian emerald from African or Brazilian emerald. It is described as ‘green on top of green’. In the Columbian mines emeralds are worked by hand and plucked from carbonaceous shale. Muzo and Chivor are two of Columbia’s most important mines. Emeralds mined in Muzo are slightly yellowish whereas those from Chivor are bluer. It is also believed that there is a symbiotic relationship between Columbian emerald and the gold of the country. The combination is therefore splendid. It is left to your imagination what jewellery might be produced by the country’s craftsmen.
BRAZIL EMERALD GEMSTONE
Brazil has been supplying emerald to the world market since the 1980s. Typical Brazilian emeralds are lighter and yellowish
AFRICAN EMERALD GEMSTONE
African countries like Zimbabwe, Zambia, Madagascar and Nigeria have deposits of beryl and are the second most leading producer of emerald. Unlike Columbian emerald, African emerald lacks the intensity of green colour. Due to the presence of a higher percentage of iron in these emeralds the green colour gets blunt and a grayish tinge takes over. Therefore it is described as ‘green on top of grey or brownish grey’.
Emerald from Zambia often has the defect of being ‘overblue’ that is when viewed under incandescent bulb it appears to be bluish. It might be mentioned here that when emerald was first discovered in Zambia it was not considered emerald at all. This was because although it was bright it had a lighter to medium hue. The confusion was deepened by the fact that it had much less inclusions and could be doubted as synthetic. Later on this doubt was cleared and Zambian emerald made emerald affordable to a lot of people..
Emeralds from Zimbabwe are smaller is size and lighter in shade. However the term ‘African emerald’ is a misnomer. It simply denotes green fluorite.
Some of the other countries, which produce emerald, are Russia, India and Australia.
RED EMERALD OR BIXBITE
This gem which is basically formed out of the mineral berl takes its colour due to the presence of manganese. It is found only in a few deposits of Utah’s Wah Wah mountain. This makes it one of the rarest gems of the world all the more so if it is facetable.
SYNTHETIC EMERALD GEMSTONE
The synthesis of emerald began in the 1930s when it
was done by a process known as Farben and the Chatham processes. However the process did not run out to be commercially much viable. Later on in the 1960s another process known as hydrothermal flux process began to be used in the production of synthetic emerald. In this method crystal nutrients are dissolved in an acidic solution of water and chemicals at a very high temperature and pressure. It is then allowed to crystallize in a cooler chamber of the reactor. This method of emerald production proved to be much viable and by 1980 as much as 500,000carats of gem had been manufactured through this process. Manufacturers Biron, Chatham, Kyocera, Gilson, Inamori, Farben, Lechleitner, Linde and others produce synthetic emeralds today.