Synthetics, simulants, and enhancements

Main articles: Synthetic diamond, Diamond simulant, and Diamond enhancement

Synthetics

Synthetic diamonds are diamond crystals that are manufactured in a laboratory, as opposed to natural diamonds which form naturally within the earth.

The gemological and industrial uses of diamond have created a large demand for rough stones. This demand has long been satisfied in large part by synthetic diamonds, which have been manufactured by various processes for more than half a century. However, in recent years it has become possible to produce gem-quality synthetic diamonds of significant size.^[41]

The majority of commercially available synthetic diamonds are yellow in color and produced by so called High Pressure High Temperature (HPHT) processes.^[42] The yellow color is caused by nitrogen impurities. Other colors may also be reproduced such as blue, green or pink which are a result of the addition of boron or from irradiation after synthesis.^[43]

At present, the annual production of gem quality synthetic diamonds is only a few thousand carats, whereas the total production of natural diamonds is around 120 million carats. Despite this fact, a purchaser is more likely to encounter a synthetic when looking for a fancy-colored diamond because nearly all synthetic diamonds are fancy-colored, while only 0.01% of natural diamonds are fancy-colored.^[44]

Producing large synthetic diamonds threatens the business model of the diamond industry. The ultimate effect of the ready availability of gem-quality diamonds at low cost in the future is hard to predict.

Simulants

A diamond simulant is defined as a non-diamond material that is used to simulate the appearance of a diamond. Diamond-simulant gems are often referred to as diamante.

The most familiar diamond simulant to most consumers is cubic zirconia (commonly abbreviated as CZ). The popular gemstone moissanite is often mischaracterized as a diamond simulant, although it is marketed as a gemstone in its own right rather than explicitly as a diamond simulant. While moissanite does look similar to diamond, its main disadvantage as a diamond simulant is that CZ is far cheaper and arguably equally convincing. Both CZ and moissanite are synthetically produced.

Enhancements

Diamond enhancements are specific treatments performed on natural or synthetic diamonds (usually those already cut and polished into a gem), which are designed to better the gemological characteristics of the stone in one or more ways. These include laser drilling to remove inclusions, application of sealants to fill cracks, treatments to improve a white diamond's color grade, and treatments to give fancy color to a white diamond.

Coatings are increasingly used to give a diamond simulant such as cubic zirconia a more "diamond-like" appearance. One such substance, which is heavily advertised, is what scientists refer to as "diamond-like carbon". This is an amorphous carbonaceous material that has some physical properties which are similar to that of the diamond. Advertising suggests that such a coating would transfer some of these diamond-like properties to the coated stone, hence enhancing the diamond simulant. However, modern techniques such as Raman Spectroscopy should easily identify such as treatment.^[45]

Identification

In the 22 November 2008 issue of New Scientist, it was stated that Russell Hemley of the Geophysical Laboratory at the Carnegie Institution for Science had discovered a technique to make diamonds via microwaves which were indistiguishable from natural diamonds. Yufei Meng, a scientist from the same laboratory, claimed that after having sent these diamonds for diamond jewellery identification, they were not identified as different from natural diamonds.^{[citation needed]} Such claims are often made for new synthetics, simulants, and treated stones, so it is important to validate how the stones were submitted for identification. For example, the "test" could simply refer to showing the stones to an unqualified jewellery shop assistant.

Properly-trained and equipped gemologists can distinguish between natural diamonds and synthetic diamonds. They can also identify the vast majority of treated natural diamonds, two exceptions being a small minority of HPHT-treated Type II diamonds and some artificially-irradiated green diamonds. "Perfect" crystals (at the atomic lattice level) have never been found to exist anywhere, so both natural and synthetic diamonds always possess characteristic imperfections, arising from the circumstances of their crystal growth, that allow them to be distinguished from each other.

Laboratories use techniques such as spectroscopy, microscopy and luminescence under shortwave ultraviolet light to determine a diamond's origin. They also use specially-made machines to aid them in the identification process. Two well-known screening machines are the DiamondSure^{[dead link]} and the DiamondView^{[dead link]}, both produced by the DTC and marketed by the GIA.

Several methods for identifying synthetic diamonds can be performed, depending on the method of production and the color of the diamond. CVD diamonds can usually be identified by an orange fluorescence. D-J colored diamonds can be screened through the Swiss Gemological Organization's^[46] Diamond Spotter. Stones in the D-Z color range can be examined through the DiamondSure UV/visible spectrometer which is a tool developed by De Beers.^[47] Similarly, natural diamonds usually have minor imperfections and flaws, such as inclusions of foreign material, that are not seen in synthetic diamonds.