An emerald is a green mineral that belongs to the beryl variety and contains trace amounts of chromium and will often contain vanadium. Beryl registers between a 7.5 and 8 on a 10 point Mohs scale which is used to measure the hardness of minerals. It is considered to be a brittle mineral which breaks easily. The word emerald comes from the Semitic word ‘izmargad’ which means green.
The quality of an emerald is graded on color, cut clarity, and crystal. When referring to crystal the term is usually used to describe transparency. In years prior to the 20th century jewelers would often use the term water to refer to the transparency. When grading an emerald both color and crystal are of great importance. Stones with a high degree of transparency are considered to be of top quality.
Emeralds have been mined in Egypt, Austria, and Pakistan. There is occasionally a rare gem which is found in Columbia. Emeralds from Columbia are usually considered to be of high quality and are the most prized of all the emeralds. You can also find emeralds in Zambia, Brazil, Zimbabwe, Madagascar, Pakistan, India, Afghanistan, and Russia. In the United States you can find emeralds in one area of North Carolina. In 1998 they were also found in Yukon, Canada.
The color of the emerald can be divided into three components which are hue, saturation and tone. Yellow and blue hues can be found with emeralds ranging in hues from yellowish green to bluish green. The primary color is green and only those gems that are medium to dark in tone and color are considered to be a true emerald. Lighter tones are of the species named green beryl. The green hue of the emerald must be vivid and brilliant. Duller gray tones are not acceptable and are much less valuable. The finest of emeralds will be a vivid green that is only slightly modified by yellow but does not have any visible gray tone.
The clarity of emeralds is graded by the eye. There must be no visible signs of inclusions and the gemstone must be vivid and flawless. If the stone is free of flaws and has an 85% green saturation hue with only 15% of the secondary hue visible it is a stone that will command a high price.
Most emeralds are treated through a lapidary process which oils the stone to improve the stone clarity. Often the oil that is used is cedar oil because it has a similar refractive index and is an accepted practice in the gem industry. There are often other oils used such as synthetic oils and polymer liquids. In the United States the Trade Commission requires disclosure of any treatment that is used to produce the stones.
It is generally accepted throughout the industry to use oils to treat emeralds but the use of green tinted oil is strictly prohibited. Laboratories have standardized the language they use to describe the grading and clarity of emeralds. The four step scale is none, minor, moderate, and highly enhanced. These categories are used to describe the enhancement of the stone and not the original stone clarity. A stone that is graded as none will probably still display some inclusions that are visible to the eye.
The popularity of the emerald has not waned over the years. They are sought after and desired by some of the world’s most affluent people. Often they are combined with other gems such as pearls or diamonds to make the expensive gemstone jewelry that is worn by the Hollywood stars. The stone has held its value through the years but there are certain qualities of emeralds that the average individual can afford to own. The vivid green stone is unlike any other gem found in the world when it comes to its rare beauty.
Copyright 2008 Paraiba International