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
Polish Luster	Vitreous
Fracture Luster	Vitreous
Fracture	Conchoidal
Hardness	7.5 - 8
Toughness	Good
Specific Gravity	3.58 - 4.41
Birefringence	None
Cleavage	Indistinct
Dispersion	0.020
Enhancements	None known
Transparency	Transparent to translucent
UV Long	Inert
UV Short	Inert
Absorption Spectrum	Bands at 570 and 700, 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