HomeMajor Colored StonesEmeraldSynthetics and its Detection for Emeralds

Synthetics

Emeralds have been synthetically produced since 1848. However, only recently have synthetic emeralds been available of the market. The synthetic emeralds currently produced are so similar to true, natural emeralds that they are virtually indistinguishable by normal means.

 

Right from beginning of this world, Emerald has fascinated this world. It was and still is favorite gemstone of ruling dynasties and elite classes around the world. In past, Indian rulers like Shah jahan was so much enamored with emerald that he decorated monument of his departed wife with plentiful of them. That magnificent monument is known as 'Taj Mahal'. Even Egyptian pharaohs used them in crowns and many were buried with them. It is considered as an auspicious gemstone to ward off any evil influence from our life. Though much has been mentioned about it, people still find it difficult to differentiate between natural and a synthetic emerald.

Natural emeralds are formed when the natural forces of the earth apply heat and pressure in due course while synthetic emeralds are formed when heat and pressure are applied to minerals after a while in a laboratory. Synthetic emeralds in other words are laboratory grown and are not mind from the ground like natural emerald. These are also less expensive in comparison to natural emeralds.


Synthetic emeralds are produced in Germany, France, and United States of America with flux growth and hydrothermal processes in laboratory. These are expensive methods and difficult to yield major results .It is mentioned that the first synthetic emerald appeared in last part of last century. One of the reasons given was extremely slow productive methodology used in synthesizing emerald.

It is always difficult to differentiate between natural and synthetic emerald because they both have the same chemical composition and crystal make-up. Previously synthetic emeralds were tested with Chelsea colour filter to found out difference between natural and synthetic emerald. but it produced limited results. After much research reputed gemologists and jewelers concluded that difference between natural and synthetic emerald can be found out by assessment of specific gravity and refractive indices of emeralds. In simple words, Specific gravity of emerald is its weight in air divided by the loss of weight in water. It is tested with density meter, a scientific instrument. Refractometer is a scientific instrument that calculates speed of luminous rays arising from the stone. Refractometer is also used to check the indexes of refraction of stone.

Major Differences
The major differences between synthetic and natural emerald are

(a) Specific gravity of a synthetic emerald (2.66) is lower than natural emerald (2.70-2.78) and refractive indices of a synthetic emerald (1.565) are lower than natural emerald (1576-1582).

(b) Flux growth and hydrothermal processes can produce synthetic emerald and due to them it shines unexciting red with ultra violet light which one does not get in a natural emerald.

(c) Synthetic emerald possesses feathery inclusion which is not to be found in natural emerald

(d) Natural emerald produce green light because of impurities but in synthetic emerald this may not be possible

(e) Clarity of natural emerald be enhanced by oiling but in synthetic emerald this cannot be done.

Since global market is flooded with synthetic and fake emeralds, veterans in this field always insist on extensive tests to be used to distinguish a natural emerald. International gemologists have ardently appealed to those who are involved in buying and selling emeralds to advise their clients to seek help of professional gemological centers to check authenticity of natural emerald.

Therefore, world-renowned gemologists advice buyers to (a) purchase laboratory-tested emerald from a certified jeweler (b) Get a certificate from the source of emerald for its identity. Major emerald producing countries like Columbia and Brazil have associations that certify exporters and sellers for quality control.

Scientific methods to distinguish a natural emerald- Any serious buyer of emerald must avail services of gemologists because gemologists always use number of laboratory tests to gauge identity of natural and synthetic emerald. At the outset, they use hand lens to check visual features like clarity and binocular microscope for features such as colour zoning, growth, and inclusion. As it is difficult to distinguish a natural emerald from synthetic emerald, a scientific instrument known as spectra scope is used. Spectroscope is an instrument that allows observer to relate a gemstone's colour to its observation spectra

Raman spectroscopy is an advanced method to judge fingerprinting inclusion of synthetic emerald. Later on, gemologists often use advanced testing instruments like energy-depressive x-ray fluorescence system (EDXRF) for further investigation. These advanced tests are performed by trained gemmologists, and only after intensive testing conclusions about natural and synthetic emerald can be made.

It is advisable to be careful with emerald because it is not only precious but one cannot differentiate between a natural and synthetic emerald without thorough knowledge of the subject. Therefore those who are buying it must first know about specific gravity of a natural emerald that is often between 2.70 to 2.78 and also refractive indices that is always between 1.576 to 1.582.

  • Hydrothermal
  • Russian hydrothermal emerald
  • Biron
  • Leichleitner
  • Flux Growth
  • Kimberly
  • Kyocera, Farben, Linde
  • Inamori - Seiko Emerald
  • Gilson
  • Igmerald
  • Nacken emerald
  • Chatham emerald
  • Gilson emerald
  • Zerfass emerald
  • Lennix emerald Flux-growth

Developed by M. Lens of France, these synthetic emeralds are grown as rectangular rather than hexagonal crystals and have a tabular habit. Their constants are slightly lower than those of the natural stone (R.1.=1.562, 1.566; D.R.= 0.004; S.G.=2.62-2.65). Two-phase and three-phase inclusions resembling feathers and particles of flux are typical, as are spiky cavities. The most characteristic features are small crystal clusters looking like rosettes. The stones show a strong red through


Linde emerald - Regency emerald

This synthetic emerald is grown using the original Linde technique and Union Carbide patents. Constants are generally close to those of the natural stone, although the S.G. is slightly lower, at 2.68. There's very little iron content, with the result that the stones have a high S.W. U-V transmission factor and a strong red fluorescence (even under a beam of high-intensity white light). Typical inclusions are wedge-shaped, dagger-like growth tubes, two-phase features stemming from phenakite crystals, and the occasional healed-crack type of feature.

Malossi Hydrothermal Emerald

Are synthetic emeralds grown by a hydrothermal technique in the Czech Republic using Italian technology.(Characterization of the New Malossi Hydrothermal Synthetic Emerald, Ilaria Adamo et al, Winter 2005 Gems & Gemology)

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