Yttrium aluminum garnet (YAG)

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Yttrium-aluminum garnet (synthetic gemstone); Wikipedia


A synthetic crystalline material composed of yttrium aluminum oxide. The name, yttrium aluminum garnet (YAG) is technically inaccurate, as garnet is a silicate mineral, but its properties are similar to garnets. Chemically, YAG is corundum (Al2O3) with some of the aluminum replaced by yttrium. Synthetic yttrium iron garnets (YIG) and yttrium aluminum garnets (YAG) are used as microwave bandpass filters in in lasers and communication networks. From about 1970, single-crystal YAGs were used for making artificial diamonds and gemstones. Colored variants and their doping elements include:

  • green (chromium)
  • blue (cobalt)
  • red (manganese)
  • yellow (titanium)
  • blue/pink/purple (neodymium, depending on light source)
  • pink, and orange.

The faceted synthetic gems have high clarity, durability, high refractive index and dispersion. YAG cuts and polishes like natural garnet, but it also has low heat sensitivity.

Raman spectrum of green synthetic YAG gemstone; RRUFF

Synonyms and Related Terms

yttrium garnet; yttrium iron garnet (YIG);

Commercial names: Diamite; Diamonite; Diamogen; Diamondair; Diamonique; Gemonair; Replique; Linde simulated diamond; Triamond

Physical and Chemical Properties

  • Luster= vitreous
  • Fracture = conchoidal
  • Fluorescence = none to moderate (colorless stones); none (blue and pink stones); strong yellow with phosphorescence (yellow stones); strong red in LW (green stones)
  • Birefringence = none
Composition Y3Al5O12
Mohs Hardness 8.5
Density 4.5-4.6 g/ml
Refractive Index 1.82-1.84
Dispersion 0.028 (weak fire)


Natural and Simulated Diamonds

Resources and Citations

  • Gem Identification Lab Manual, Gemological Institute of America, 2016.
  • G.S.Brady, Materials Handbook, McGraw-Hill Book Co., New York, 1971 Comment: p. 178