Beware of diamond simulants if you are after buying a real genuine diamond!

Here we will try to teach you about the different ways diamonds are artificially made in labs. On the other hand for those who want a cheaper buy this might be a good choice if you are making an informed decision.

As the market for diamonds continues to grow and diamondsincrease in value and price, many people have looked for options to replacethese diamonds. These imitations or simulants can be natural, artificial or acombination of the two and are used to replace diamonds at much lesser costs.

Gemisimo Advice: Always Check the Diamond Report prior to buying!!!

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Diamond Stimulants

It is therefore all the more important that diamond buyers be aware of the variousdiamond simulants available in the market today. It is also important tounderstand the difference between synthetic diamonds and simulants, as manyoften confuse the two terms. Synthetic diamonds are quite rare and have achemical composition similar to natural diamonds. Simulants on the other handhave a chemical composition much different from diamonds. Secondly whilesynthetic diamonds are produced in laboratories in sizes suitable for cutting,simulants may be natural, artificially or a combination of the two.

History

The history of diamond simulants is as old as the history of diamonds . For many years, the options to replace diamonds were few. The mostpopular options during 1700 were natural stones that would shine like diamonds.These stones were usually made out of glass, the refractive index of which wasincreased by using lead, thallium and alumina. During the 1900s, manyartificial simulants arrived on the scene. These included synthetic whitesapphire and spinel. During 1947 optically enhanced simulants like syntheticrutile arrived on the scene followed by the commercial launch of in strontiumtitanate 1955. While each simulant was launched with more enhanced diamond like features , drawbacks were also quick to be discovered. Strontium titanate wassoft and brittle and in the 1970s began being replaced by synthetic garnets.Yttrium aluminum garnet (YAG) was introduced in the late 1960s followed byGadolinium Gallium Garnet (GGG). In 1976 Cubic Zirconia and many othermaterials, fast entered into the simulant scene in a big way, and continue tobe popular diamond simulants even today. We will try to cover all these in this article.

Diamonds vs. diamond simulants at a glance

Properties of diamond

Chemical composition: Carbon

Hardness on Mohs scale: 10

Refractive index: 2.42

Specific gravity: 3.52

Natural Diamond simulants

This section comprises of natural minerals that resemblediamonds when they are cut. However there are very few such minerals, as thepresence of trace impurities in such materials often reflect color. Naturalsimulants used through history include,

Natural zircon (ZrSiO4)

Natural zircon was popularly used as a simulant duringancient times. The white color of the crystal was obtained by heating zircon ofcolors like yellowish-brown and green. The stone was noted for its goodbrilliance and fire. However, natural zircon proved to be very different fromdiamonds on closer examination. The simulant's hardness is approximately 7 andcan easily be scratched by topaz. Secondly, this simulant also shows wear onthe girdle edges and lesser brilliance.

Colorless scheelite

This was less prevalent than natural zircon but was alsoused as a simulant. While the stone enjoyed high dispersion, it demonstratedless hardness, equal to 4.5. Also there is comparatively less availability ofnatural gem quality scheelite and synthetic scheelite has been more popularlyused.

Carbonate cerrusite

These naturally occurring crystals also enjoy high lusterand dispersion, making them look very attractive. However these are rarely usedas diamond simulants as they are soft, fragile, difficult to cut and have ahigh density.

Sphalerite

Also known as zinc blende, this material has a highrefractive index and dispersion. On the flipside however, this stone has a lowhardness and a perfect dodecahedral cleavage.

Topaz

With a high hardness of 8, topaz was a popular diamondsimulant for many years. However, the stone has low refractive index andbecause of less fire than diamonds, today it is rare to see the usage of topaz.Gemologists can also differentiate between topaz and diamonds because theinclusions present in topaz are very different from those found in diamonds.

Artificial simulants

Artificial simulants have grown in popularity and usagesince many years as these are easy to produce and demonstrate results muchcloser to real diamonds.

Synthetic white sapphire

These have been used for a long time as simulants and havehigh hardness of 9. However the stone has a dull shine and because it isanisotropic, it can easily be detected through a polariscope. The stone has arefractive index that falls within the range of a refractometer and onobservation through a loupe, one can see air bubbles.

Synthetic spinel

This was used as a successful diamond simulant for a longtime, for its hardness of 8, but its fluorescence in bluish white hue underLWUV and a blue green hue under SWUV, have made it easily detectable fromdiamonds.

Glass

Glass has been a popular diamond simulant, mainly because ithas been possible to give it brilliance and shine with different compositions.However glass is quite different from diamonds and examination with apolariscope can show the difference. Air bubbles can be a giveaway and glassalso often shows swirl marks.

Synthetic rutile (TrO2)

This has a high refractive index as compared to diamonds andthus gives a high brilliance. However rutile is anisotropic, and its great fire(eight times more than diamonds) makes the stone appear too colorful. Also thissimulant is much softer than diamond, ranging at point 6 on the Mohs scale,making it easier to differentiate from diamonds.

Strontium titanate (SrTiO3)

This simulant looks very much like a diamond, but is not inmuch use today mainly due to the usage of Cubic Zirconia. The stone isdifferent from diamond because of its high quantity of fire, which makes thestone appear highly colorful. Also it is very soft, a factor that does notallow for giving it a good polish and finish.

Yttrium Aluminum Garnet (YAG) Y3Al3O12

This simulant proved to be highly successful and much usedwhen it was first introduced in the market. The main factors that make YAGresemble diamonds is its colorlessness, high hardness and good refractiveindex. The way to differentiate a YAG from diamond is to observe it under aloupe. Small air bubbles and polishing lines typical to YAG can be observed inthis manner.

Gadolinium Gallium Garnet (GGG) Gd3Ga5O12

The properties of this simulant also resembles those ofdiamonds quite closely, making the stone a successful simulant. Theseproperties include a high refractive index and fire. However expert gemologistscan differentiate a GGG from a diamond through its brown undertone andsoftness. Air bubbles and triangular leaflet like inclusions can also be seenin GGG.

Cubic zirconia

In today's diamond market, cubic zirconia is the mostpopular and most effective diamond simulant. This is the precise reason why,this stone is produced in high quantities. The stone is difficult todistinguish from diamonds because it disperses light similar todiamonds. Also this has a high refractive index, hardness (8 on Mohs scale) anddispersion. Gemologists differentiate cubic zirconia by measuring the specificgravity of the stone, which is higher than that of diamonds. Another test thatmany gemologists follow is to bring the stone to their tongue. Diamond is verycold to touch while cubic zirconia does not feel as cold. Vapor tests orrapidographs are other methods used to differentiate diamonds from cubiczirconia.

Composites

Besides natural and artificial simulants, diamond imitationscomprising of both natural and artificial elements are also present. Onepopular example of such a combination is doublets. These stones have severalparts, starting from two onwards. Cases of such simulants exist where a thinlayer of diamond is attached to an artificial stone like cubic zirconia or YAG.Another example of composites, involves doublets with cubic zirconia corecovered with amorphous diamonds created in the laboratory. These stones arehighly deceptive in nature as a quick examination only reveals the thin layerof

How experts differentiate diamonds from simulants

Diamonds are known for their hardness and brilliance. Basedon diamond's intrinsic special features, gemologists follow one or acombination of the below measures to identify whether a particular stone is adiamond or not.

• Diamond has the highest degree of hardness on the Mohs scale, which implies that a diamond can only be scratched with a diamond. Sapphire is the next hardest stone on the scale and gemologists usually scratch the stone to be tested with sapphire. Diamonds do not get scratched by sapphires, while other imitations usually do.
• Diamonds are also noted to have lower specific gravity than most other imitations. Thus when stones to be tested are put in di-iodomethane, a heavy liquid, diamonds sink slowly as compared to other imitations that comparatively sink faster.
• Checking for inclusions typical to diamonds and other imitations also assists gemologists in identifying diamonds.
• Spectroscopic examinations are also conducted and diamonds reveal their own characteristic absorption bands. Reflectometers are also used to check the degree of light reflected from the stone's surface.

However there are many imitations that one must be aware of.Buying diamonds from trusted sellers is probably the first step that careful buyers must taketo avoid diamond stimulants. Secondly purchasing certified diamonds is also important.

Finally in case of doubt, diamond buyers always have the right to get thediamonds tested at a local diamond laboratory of repute. Diamond imitations areprevalent and often difficult to detect. However today laboratories do havesophisticated techniques to make the process easier.