GGG (Gallium Gadolinium Garnet): an artificial material produced by the Czochralski Method, chemically represented by the formula Gd3Ga5O12. Transparent and colorless, with a luster ranging from vitreous to sub-adamantine, it was used in jewelry during the 1970s as a Diamond simulant before being gradually replaced by other simulants considered more attractive, such as YAG, Cubic Zirconia, and synthetic Moissanite. It crystallizes in the Cubic System, making it singly refractive, and has the same crystal structure as Garnets, despite lacking silicon, which is characteristic of Garnet chemistry—hence its classification as a Garnetoid. It differs from Diamond by its weak dispersion, typically showing blue flashes on the pavilion.
