Gadolinium gallium garnet (GGG, Gd3Ga5O12) is a synthetic crystalline material of the garnet group, with good mechanical, thermal, and optical properties.
It has a cubic lattice, a density of 7.08 g/cm3 and its Mohs hardness is variously noted as 6.5 and 7.5.
During production, various dopants can be added for colour modification.
The material is also used in fabrication of various optical components and as a substrate material for magneto–optical films (magnetic bubble memory).
[3] Another interesting aspect to this synthetic gemstone is that it exhibits both fluorescence under UV, and Phosphorescence (glow-in-the-dark) properties.