Yttrium aluminum garnet (YAG)

Description

A synthetic crystalline material of the garnet group. Synthetic yttrium iron garnets (YIG) and yttrium aluminum garnets (YAG) are used as microwave bandpass filters in communication networks. Single-crystal YAGs are also used in lasers and 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 like natural garnet, with polishing being performed with alumina or diamond (50,000 or 100,000 grit) on common polishing laps. YAG has low heat sensitivity.

Synonyms and Related Terms

yttrium garnet; yttrium iron garnet (YIG);

Commercial names: diamite; diamonite; diamogen; 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)

Comparisons

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

• Web Elements at http://www.webelements.com/webelements/elements/text/Y/hist.html

• Wikipedia: Yttrium aluminum garnet