Garnet shades of green, beige, brown, gray, and blue, but in incandescent light, they appear a reddish or purplish/pink color. This is the rarest type of garnet. Because of its color-changing quality, this kind of garnet resembles Alexandrite. Andradite is a calcium-iron garnet, CaFe(SiO), is of variable composition and may be red, yellow, brown, green or black. The recognized varieties are topazolite (yellow or green), demantoid (green) and melanite (black). Andradite is found both in deep-seated igneous rocks like syenite as well as serpentines, schists, and crystalline limestone. Demantoid has been called the "emerald of the Urals" from its occurrence there,
Yttrium aluminium garnet has low heat sensitivity. As a synthetic gemstone YAG has numerous varietal and trade names, as well as a number of misnomers. Synonymous names include: "alexite", "amamite", "circolite", "dia-bud", "diamite", "diamogem", "diamonair", "diamone", "diamonique", "diamonite", "diamonte", "di'yag", "geminair", "gemonair", "kimberly", "Linde simulated diamond", "nier-gem", "regalair", "replique", "somerset", "triamond", "YAIG", and "yttrium garnet". Production for the gem trade decreased after the introduction of synthetic cubic zirconia; there was little production. Some demand exists as synthetic garnet, and for designs where the very high refractive index of cubic zirconia is not desirable. Neodymium-doped YAG (Nd:YAG) was developed in the early 1960s, and