Identify a Created Diamond
A lab diamond is a real diamond in every way, but there are various methods used to identify it as laboratory-grown rather than mined. Consumers can perform some checks themselves, others require assistance of a jeweler and some tests are only available to the largest gem labs.
At the scientific level, diamonds can be categorized into four types, based on the impurities in the carbon lattice, at the atomic level. These impurities are not the same as inclusions, and need powerful equipment such as an infrared spectrometer to detect the type of a diamond.
- Type Ia - About 98% of mined diamonds
- Type Ib - All synthetic yellow diamonds, 0.1% of mined diamonds (fancy yellow & green)
- Type IIa - All synthetic colorless diamonds, 1-2% of mined diamonds (colorless & pink)
- Type IIb - All synthetic blue diamonds, 0.1% of mined diamonds (blue)
Electrical conductivity tests are used to test for moissanite, since this simulant is electrically conductive. All yellow and mined white diamonds are not electrically conductive, however all blue diamonds–mined and grown alike–are electrically conductive, due to the boron in the diamond lattice. In addition, some HPHT-grown white diamonds have trace amounts of boron in them, so may be electrically conductive, despite being colorless. Electrical conductivity tests may be accurately used for yellow diamonds, mined and CVD-grown white diamonds though will give false positives for all blue diamonds, and may give false positives for some HPHT-grown white diamonds.
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 solution the diamond is grown in.
A cathodoluminescence (CL) spectrometer can show different growth sectors in a diamond. Mined diamonds only have octahedral growth sectors, while in a vast majority of HPHT created diamonds, they 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. Both of these machines are expensive and are usually only available at the major gemological labs like GIA, IGI and EGL.