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By Reviewed By Andreas Zabczyk Apr 01, 2008 Updated Jan 24, 2019

Simulants Vs. Synthetics

When we talk about fake gemstones in the gem business we always distinguish between gemstones that are synthetic and those that are simulants. A simulant has an appearance similar to that of a natural gemstone, but has different optical, physical, and chemical properties. Cubic zirconia and moissanite are examples of well-known diamond simulants. A trained gemologist with the right instruments can easily separate simulants from the natural gems they simulate. For example, moissanite shares many optical properties with genuine diamond, it even fools thermal testers. But moissanite is doubly refractive while genuine diamond is singly refractive, and a gemologist can tell the difference by visual inspection alone.

Moissanite Gemstone
Moissanite Gemstone

Cubic zirconia and moissanite are lab-created materials, but a simulant may also be a natural gemstone. Natural, white zircon was once used as a diamond simulant, for example; and some of the most important rubies in the world turned out to be natural spinels. A real gem can be deemed a fake if it is presented as something else, usually a more expensive gem material.

Natural Moissanite

A synthetic gemstone, on the other hand, is a laboratory-created gemstone that has essentially the same appearance and optical, physical and chemical properties as the natural material (if such an identical natural material exists). So a synthetic diamond is a real diamond. Synthetic moissanite, by contrast, is only a diamond simulant; it is, however, real moissanite (though natural moissante exists in only minute quantities). Since synthetic moissanite is actually quite expensive, moissanite simulants have even started to appear on the market.

It is possible for a gemstone to be both synthetic and a simulant. A lab-grown spinel passed off as natural sapphire, is a synthetic spinel and a sapphire simulant.

Synthetic lab crown Sapphire
Lab-created Sapphire

A simulant, by definition, is intended to give the appearance of a natural gemstone. The intent is not always fraudulent of course; cubic zirconia and moissanite are almost always sold under their own names. The goal is to provide a lower-cost gemstone that exhibits brilliance and fire somewhat similar to diamond. Selling these simulants is a perfectly respectable business, provided that the gems are correctly identified.

Most of the business in synthetic gem material is also entirely respectable. Synthetic sapphire, for example, is used for mechanical parts (tubes, rods, bearings, and other machined parts), scratch-resistant watch crystals and windows for optical equipment and spacecraft, as well as for lasers. Naturally, there is a market for lower cost jewelry made with synthetic gems. Some people would prefer to have a ring with a synthetic sapphire exhibiting the same hardness, brilliance and luster as a natural sapphire, rather than buy a ring with a lesser natural gemstone for the same price. It is also possible to produce synthetic sapphires in colors not seen in nature, which is apparently of interest to some buyers.

Cubic Zirconia
Cubic Zirconia

It is fair to say that the presence of synthetics and simulants in the market has not undermined the market for genuine natural gemstones. Synthetics remind us that natural gemstones are incredibly rare and unusual products of nature. To the expert gemologist, synthetics betray their artificial origin - they have none of the natural inclusions that are the fingerprints of natural stones. In one sense, the synthetic stones are too perfect; they lack natural imperfections. However, they have their own imperfections - they have curved growth lines that show how the crystals formed in layers in the labratory.

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