YAG and GGG
As technology advances, scientists developed new lab-grown crystals with garnet-like cubic crystal structure (note they are not synthetic garnets) to be used as diamond simulants. The two of greater interest in jewelry are: Yttrium Aluminium Garnet (YAG, 1970) and Gadolinium Gallium Garnet (GGG, 1973).
See top row, second stone from right – GGG, and bottom row, second stone from right – YAG.
From top left clockwise direction: Natural diamond, synthetic rutile, gadolinium gallium garnet (or GGG), synthetic spinel, strontium titanate, synthetic corundum, yittrium aluminum garnet (or YAG), and colorless zircon.
Both have relatively good hardness and a wider range of body colors. Aggressive promotion boosted YAG’s commercial success. One of its most famous promotions was its use for Cartier’s replica of the 69.43 carat Taylor-Burton diamond. For many years, YAG remained the most popular diamond simulant. GGG has high RI and dispersion, almost the same as diamond, thus showing similar fire.
YAG is fairly easy to differentiate from a diamond as it tends to appear glassy and “lifeless.” While GGG resembles closer to diamond because of the similar dispersion, it’s much heavier than a diamond of the same size. For a given size, YAG and GGG weigh 50 – 100% more than a diamond. Both have higher Specific Gravitiy (SG) than diamond (YAG 4.55, GGG 7.05, Diamond 3.52). Like all other simulants except for synthetic moissanite, they are poor thermal conductors, thus easy to tell apart with a thermal tester.
In terms of cost of production, YAG and GGG (especially GGG) are far more expensive than other simulants. And as new and better simulants appear on the market, for instance Cubic Zirconia (CZ) in 1976, both these materials lost its appeal and became infrequently used for jewelry purposes. They remain in industrial use for lasers and other optical electronic components.
CZ
Today, the most common diamond simulant is synthetic cubic zirconia (CZ). Dubbed synthetic because CZ has a very rare natural counterpart. And please do not confuse CZ and zircon because of the similar names. They are entirely different materials.
The introduction of CZ was a near-instant success in 1976. Owing to its high RI and dispersion, it’s almost as brilliant and lustrous as a diamond, making it a credible simulant for diamond.
CZ is perfectly colorless though it can be produced in a range of colors. The production of colored CZ was inspired by strong public interest in fancy-colored diamonds.
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While CZ is the most popular diamond simulant, it is also an important jewel in its own right, evidenced by its colorless and colored forms set into fashionable but affordable jewelry.
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Jem Boxx 