This is very different from the term "synthetic", which (for the gemstone industry) refers to a material that has the same essential chemical composition and atomic structure as the original, but was in fact grown artificially in a laboratory.
Diamond holds one of the highest value-per-weight materials in the world, so naturally a lot of people want to create 'fake' or faux versions of the precious gemstone.
Today let's take a look at some of the most common fakes, imitations or simulants out there on the diamond market. First up, we have the most commonly used stone; cubic zirconia. Now this refers to cubic crystalline form of zirconium dioxide.
CZ, as it's more commonly known, is the synthetic counterpart to baddeleyite, which was discovered in 1892, and is the yellowish natural form of zirconium oxide. CZ is extremely popular because its optical properties are very close to those of diamond. Although it only possesses a hardness of 8.5, cubic zirconia fashioned into round brilliant cuts, display more 'fire' than diamond, due to a higher dispersion rate. Much of the trade involving faux diamonds make use of CZ crystals for their brilliance and scintillation, echoing the 'feeling' of diamond, with much lesser costs.
Lately, several proprietary brands follow the trend of concocting their own slightly altered recipe for creating cubic zirconia. Through their efforts, they claim increases in brilliance, hardness, and other properties- however these minor trace impurities are not enough for most laboratories to change their label from cubic zirconia to something else.
Next up, we have synthetic moissanite. This material is typically more expensive than CZ, but poses a different set of difficulties when separation from diamond is needed. Standard pen-hold thermal detectors (diamond detector machines), will often label moissanite as diamond, due to their very close thermal conductivity ratings. Dual or electronic conductivity testers may have a better chance at detection, but we've often seen these machines misread stones as well. Moissanite however, is a doubly refractive stone, and splits light rays that pass through its material, unlike diamond which is singly refractive. Moissanite also displays a lot more fire (dispersion than diamond), as pictured below.
After CZ and moissanite, secondary imitators of diamond are glass, white sapphire (natural or synthetic), rock crystal quartz, and synthetic colorless garnets like gadolinium galium garnet and yttrium aluminum garnet. These stones also have appearance similarities to diamond, but not as much as the previously mentioned high rankers. Their gemological properties allow gemologists to properly separate them from diamond as totally different species of gemstones.
