Yttrium aluminium garnet (Ce:YAG) is used as a phosphor in cathode ray tubes and white light-emitting diodes, and as a scintillator. YAG for a period was used in jewelry as a diamond and other gemstone simulant. Colored variants and their doping elements include: green (chromium), blue (cobalt), red (manganese), yellow (titanium), purple (neodymium), pink, and orange. As faceted gems they are valued (as synthetics) for their clarity, durability, high refractive index and dispersion. The critical angle of YAG is 33 degrees. YAG cuts like natural garnet, with polishing being performed with alumina or diamond (50,000 or 100,000 grit) on common polishing laps. YAG
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