Know Your Emerald

by Erum Ali Qureshi

Common identification features of emerald are listed below along with those of its common synthetic stones, imitations and simulants. The information is intended to be a ready reference to give you a fair idea as to the identity of a gemstone on visual examination. Suggestions and queries from readers about the topic are encouraged.

Know your emerald


Common identification features of emerald are listed below along with those of its common synthetic stones, imitations and simulants. The information is intended to be a ready reference to give you a fair idea as to the identity of a gemstone on visual examination. Suggestions and queries from readers about the topic are encouraged.

 

emerald

 

A synthetic emerald is an emerald that is grown in a laboratory as opposed to being formed under the surface of the earth. There are many methods to do this: Hydrothermal, flux melt method etc. Emeralds grown by each of these methods have distinctive inclusions that help gemologists identify them for what they are.

Imitations or simulants are stones that imitate emeralds. For example a dyed green quartz, or green jadeite or green glass. These are totally different materials that imitate (or pretend to be) an emerald. Their physical and chemical properties too are completely different from those of an emerald. These can be easily identified on the basis of standard gemological tests that determine their specific gravity, refractive indices and absorption spectrum. Trained and experienced gemologists, jewelers and gemstone dealers may even sometimes be able to identify these on a thorough visual examination of the stone.

Beryl

The Beryl family of gemstones consists of emerald, aquamarine and Morganite. Color is the one feature that is most important in this variety of gems. Emerald without doubt is one of the most sought after gems and the first clue to a green stones identity will be its color.

Hardness

Emeralds are particularly brittle since it rates as 7 1/2 on the Moh's scale of hardness. Its luster is vitreous which means that it will have a shine but one that is slightly subdued.

Natural and Synthetic emerald inclusions

Almost all natural emeralds contain inclusions and these are a sure-shot way to identify the stones. Sometimes the inclusions are so typical that it may even be possible to prove the country of origin-though this practice is not widely prevalent.

Natural emeralds from few prominent locations may have the following inclusions:

Inclusions Description Locality
Three-phase inclusions It is a liquid-filled cavity containing a solid crystal and a gas bubble Columbia
Two-phase inclusion Liquid filled cavity with a gas bubble India
Tremolite needles Usually needle like crystals or fiber-like inclusions Zimbabwe
Mica flakes Flaky inclusions Present in emeralds from many localities
Actinolite crystals Rod-like segmented inclusions Present in emeralds from many localities

Synthetic emeralds on the other hand display flux droplets, which are drop like inclusions or wispy veil like inclusions that appear twisted within healed fractures. Emeralds grown by the Hydrothermal method are often inclusion-free but may sometimes contain spiky nail-head inclusions which as the name suggests, look very much like tiny nail-heads.



Emerald Pendant - Treated Emerald

In general a synthetic emerald will be relatively cleaner (free from inclusions) than a natural stone. Natural stones will almost always have cracks, fissures, inclusions or small chips owing to emerald's brittle nature though rare well-preserved specimens are known to be free of these blemishes.

Another point to be noted here is that synthetic emeralds are emeralds chemically and physically- the only difference is that these were created in a laboratory as opposed to under the surface of the earth. It is incorrect to refer to them as 'fakes' or imitations.

Treatment

Many emeralds for commercial sale are treated with oil or polymer resin to fill surface reaching fractures or cracks and fissures inherent in the stone. This improves the color and clarity albeit temporarily. Indications of the stone being oiled are stains on the parcel paper or on your fingers as you handle the stone.

Composite stones

Emerald doublets or triplets are rampant on the market. These consist of two pale colored stones (glass base and synthetic spinel top, or glass base and colorless beryl or rock crystal top) cemented with a layer of green paste or foil. Such stones when set are difficult to detect. These are also known as 'Soude emeralds' and are easily detected when immersed in water and viewed side-ways.

In set stones, when viewed under magnification it may be possible to see gas bubbles trapped between the layers.

Although there are myriad possibilities for confusion with other similar colored stones a thorough examination under 10X and experience go a long way in identifying natural emerald from synthetics, imitations or simulants. However in order to be absolutely sure it is imperative the stone is checked by a trained gemologist with the right equipment.

Common gemological terms used in this article

Moh's scale
Moh's scale is a scale depicting hardness in solid substances. Talc is the softest solid rating 1 on the scale and diamond the hardest rating 10.

Luster
Luster refers to the surface appearance of a gemstone. 'Shine' to the layman. Luster in gemstones is described as vitreous (glass like), adamantine (like a diamond), sub-adamantine, chalky, earthy, waxy etc.

Flux melt and Hydrothermal
Manufacturing procedures for synthetic emeralds
 

 
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