Lab-Grown Diamond Identification

Diamond synthesis, regardless of if it occurs deep in the Earth or in a production facility, is a complex phenomena depending on a limitless number of factors. It is not possible to find or create an ideal environment for diamond crystallization. That is why no perfect diamond exists. All diamonds, whether natural or synthetic, have all sorts of imperfections – inclusions, impurities, crystal lattice defects, etc. Different growth environments result in different sets of imperfections. However, these imperfections do not constitute a diamond – both mined and lab grown are real diamonds regardless of imperfections – but make it unique. A neverending study of diamond imperfections lead research institutions and gemological laboratories to the development of methods to distinguish lab grown diamonds from their natural counterparts. Some methods are quite simple, and consumers can perform those checks themselves. Others require assistance of an experienced jeweler, while some tests are only available at certain advanced research and gemological laboratories.

Disclosure

close-up of laser inscription
All of our polished diamonds over .30 carats are independently graded by a major gemological laboratory, primarily EGL USA. The certificate clearly identifies the diamond as laboratory grown. The diamond itself is laser inscribed on the girdle with both the certificate number and "AOTC CREATED", which can be read with 10x magnification.

Diamond Tester

example diamond tester
Diamonds can be tested with simple testers available at most jewelers. These commonly test for either thermal or electrical conductivity. Diamonds conduct heat extremely well, while most simulants do not. Thermal tests accurately identify lab-grown diamonds as real diamonds. Electrical conductivity tests are used to test for moissanite, since this simulant is electrically conductive. White and yellow diamonds are not electrically conductive, however all blue diamonds – mined and grown alike – conduct electricity due to the presence of boron in the diamond lattice. Electrical conductivity tests may be accurately used for white and yellow diamonds, though will give false positives for all blue diamonds. Diamond testers do not differentiate between natural and lab-grown diamonds.

Color

orange-yellow and blue diamonds
Most lab grown diamonds are currently produced in yellow or blue colors. These colors are very rare in nature and as a result are quite expensive and not commonly available. Diamonds of "fancy intense" or "fancy vivid" blue, yellow and especially orange yellow colors have a good chance of being lab grown, though the color alone is not a conclusive indicator.

Inclusions

close-up of a metallic inclusion
Nearly all diamonds, mined and grown alike, have tiny inclusions that affect their clarity. Mined diamonds are grown in molten rock deep inside the earth and their inclusions are most commonly feathers, crystals, pinpoints and clouds. Lab created diamonds are grown in molten metal and as a result the most common inclusion is metallic. Metallic inclusions do not occur in mined diamonds, and these inclusions can usually be identified with 10x magnification. In diamonds with SI clarity or better, inclusions–regardless of type–cannot be seen with the unaided eye.

Advanced Equipment

There are a few advanced machines that can correctly identify lab created diamonds. Fourier transform infrared spectrometer (FTIR) or energy dispersive X-ray fluorescence (EDXRF) can both detect traces of metal in a diamond, which comes from the molten metal catalyst the diamond was grown in.

A cathodoluminescence (CL) spectrometer can show different growth sectors in a diamond. Mined diamonds only have octahedral growth sectors, while a vast majority of HPHT created diamonds have both octahedral and cubic growth sectors.

DeBeers has developed two machines that can properly identify synthetic diamonds. The first, DiamondSure, measures light absorption at a very specific wavelength and is used as a preliminary check. The more advanced and expensive DiamondView machine uses shortwave ultraviolet imaging to look at fluorescence patterns in the diamond. This machine is similar to the cathodoluminescence spectrometer. Both of these machines are expensive and are usually only available at the major gemological labs like GIA, EGL, and IGI.