Gahnospinel Value, Price, and Jewelry Information

Gahnospinel Value

Highest values go to pure blue, size and clarity.

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Fine Color Blue: B 5/5

Blue	.5 to 2 carats	2 to 4 carats	4 carats plus
Faceted	to /ct	to /ct	to /ct

Fine Color Red: R, slpR 5/5

Red	.2 to 1 carat	1 to 5 carats
Faceted	to /ct	to ,000/ct

Pink	.5 to 1 carats	1 to 3 carats	3 carats plus
Faceted	to /ct	to ,000/ct	to

Fine Color Purple: P 5/5: P, rP, bP, V 5/4

Purple	.5 to 1 carats	1 to 3 carats	3 carats plus
Faceted	to /ct	to ,800/ct	to ,000/ct

Fine Color Orange: O, rO 5/5

Other Colors	.5 to 1 carats	1 to 5 carats	5 carats plus
Faceted	to /ct	to /ct	to ,000/ct

Star Spinel	All sizes
	to /ct

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Data	Value
Name	Gahnospinel
Is a Variety of	Spinel
Crystallography	Isometric.
Refractive Index	1.716-1.780
Colors	Green or blue, usually dark in tone
Luster	Vitreous.
Polish Luster	Vitreous.
Fracture Luster	Vitreous.
Fracture	Conchoidal
Hardness	7.5 - 8
Specific Gravity	3.58-4.41
Birefringence	None.
Cleavage	Indistinct
Dispersion	0.020
Luminescence	Inert.
Wearability	Good
Enhancements	None known.
Transparency	Transparent to translucent
UV Long	Inert
UV Short	Inert
Absorption Spectrum	Bands at 5700 and 7000, not always present.
Phenomena	None.
Identifying Characteristics	Dark tone
Formula	(MgZn)Al2O4
Pleochroism	None.

Gahnospinels from Sri Lanka

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by International Gem Society