Gadolinium Gallium Garnet (GGG)

A synthetic crystalline material, related to the garnet group of minerals with which it shares the same atomic structure.

It has been used, particularly in the early 1970s, as a diamond simulant.
General Information
Other Names/Trade Names:
Chemical Formula
Gd
 
3
Ga
 
5
O
 
15
Ulrich Henn and Claudio C. Milisenda, Gemmological Tables (2004)
Physical Properties of Gadolinium Gallium Garnet
Mohs Hardness6.5
Ulrich Henn and Claudio C. Milisenda, Gemmological Tables (2004)
Specific Gravity7.05
Ulrich Henn and Claudio C. Milisenda, Gemmological Tables (2004)
Optical Properties of Gadolinium Gallium Garnet
Refractive Index1.97 to 2.03
Ulrich Henn and Claudio C. Milisenda, Gemmological Tables (2004)
Optical CharacterIsotropic
Ulrich Henn and Claudio C. Milisenda, Gemmological Tables (2004)
Colour
Colour (General)Colourless, brown, gren, yellow, lilac, blue, red, pink
Ulrich Henn and Claudio C. Milisenda, Gemmological Tables (2004)
TransparencyTransparent
Ulrich Henn and Claudio C. Milisenda, Gemmological Tables (2004)
Fluorescence & other light emissions
Fluorescence (Short Wave UV)Common weak brownish to pinkish orange
Herve Nicolas Lazzarelli, Blue Chart Gem Identification (2010)
Fluorescence (Long-Wave UV)Inert to brownish-yellow
Herve Nicolas Lazzarelli, Blue Chart Gem Identification (2010)
Crystallography of Gadolinium Gallium Garnet
Crystal SystemIsometric
Ulrich Henn and Claudio C. Milisenda, Gemmological Tables (2004)
Further Information
Mineral information:Gadolinium Gallium Garnet information at mindat.org
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