:Gadolinium gallium garnet

{{Short description|Synthetic crystalline material of the garnet group}}

{{Infobox mineral

| name = Gadolinium gallium garnet

| category = synthetic mineral

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| formula = {{chem2|Gd3Ga5O12}}(Gia), Gemological. Gem Reference Guide. City: Gemological Institute of America (GIA), 1988. {{ISBN|0-87311-019-6}}

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| color = transparent, colorless to light brown or yellow. May also be orange or blue.

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| system = cubic

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| mohs = 6.5 (other sources 7.5)

| luster = vitreous to subadamantine

| polish = vitreous to subadamantine

| refractive = 1.970 (+.060)

| opticalprop = Single refractive

| birefringence = none

| dispersion = .045

| pleochroism = none

| fluorescence= moderate to strong pinkish orange in shortwave

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| gravity = 7.05 (+.04, -.10)

| density = 7.08 g/cm³

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Gadolinium gallium garnet (GGG, {{chem2|Gd3Ga5O12|auto=1}}) is a synthetic crystalline material of the garnet group, with good mechanical, thermal, and optical properties. It is typically colorless. 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. Its crystals are produced with the Czochralski method. 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).J. F. Greber "Gallium and Gallium Compounds" in Ullmann's Encyclopedia of Industrial Chemistry, 2012 Wiley-VCH, Weinheim. {{doi|10.1002/14356007.a12_163}} It also finds use in jewelry as a diamond simulant. GGG can also be used as a seed substrate for the growth of other garnets such as yttrium iron garnet.{{cite book |first1=U. |last1=Holm |first2=H. |last2=Sohlstrom |first3=T. |last3=Brogardh |editor-first1=Ralf T |editor-first2=Rainer |editor-last1=Kersten |editor-last2=Kist |title=Yig-Sensor Design For Fibre Optical Magnetic Field Measurements |series=2nd Intl Conf on Optical Fiber Sensors: OFS'84 |publisher=Proc. SPIE 0514, 2nd Intl Conf on Optical Fiber Sensors: OFS'84 |year=1984 |isbn= |volume=514 |pages=333–6 |doi=10.1117/12.945109 |s2cid=107371333 }}

Another interesting aspect to this synthetic gemstone is that it exhibits both fluorescence under UV, and Phosphorescence (glow-in-the-dark) properties.