Stone

RI min

RI max

Dens min

Dens max

Colour

Location

Info

Spectrum

UVS

UVL

Reference

Gahnospinel

1,715

1,754

3,6

4,06

blue, bluish violet, violet

Sri Lanka

The Journal of Gemmology 1986 Vol20, N°3, p157-160

Gahnospinel

1,723

1,752

3,72

4,05

blue, bluish violet, violet

Sri Lanka

the higher d (Zn content: 7% to 24%), the higher n

Zeitschrift der Deutschen Gemmologischen Gesellschaft 1985 34, Nr3/4, p92-97

Gahnospinel

1,742

1,742

3,96

3,96

cobalt blue

1,01ct, transparent

Gems & Gemology 2022 winter, p 476

Gahnospinel

1,754

1,754

4,1

4,1

blue

11.34ct, transparent

Gems & Gemology 2019 Spring, p92-93

Gahnospinel

3,5

3,5

blue

Nigeria

4 crystals, IR > 1.788 ; close to endmember gahnite

bands in the blue (Fe)

inert

inert

Gemmology Today 2019 September, p5-8

Stone

RI min

RI max

Dens min

Dens max

Reference

Gahnospinel

1.715

1.754

3.58

4.06

Gemme, Dati per l'identificazione, P. De Stefano et al, 1993 

Gahnospinel

1.715

1.754

3.58

4.06

Bestimmungstabellen für Edelsteine, Birgit Günther, 2008 

Gahnospinel

1.716

1.754

3.6

4.06

Gemmological Tables, Ulrich Henn, 2004 

Gahnospinel

1.725

1.754

3.58

4.06

http://www.geminterest.com 

Gahnospinel

1.725

1.753

3.58

4.06

Tables of Gemstone Identification, Roger Dedeyne, Ivo Quintens, 2007 

Gahnospinel

1.74

1.75

3.9

4.06

John Sinkakas, Gemstone and mineral data book,1972 

Gahnospinel

1.74

1.74

3.75

3.75

Gems, R Webster, 5th edition 1994 

Gahnospinel

1.74

1.78

3.61

4.41

Gemology Tools Professional 2010

Stone

Colour

Cause of colour

Reference

Gahnospinel

blue

Fe²+ in octahedral coordination

Gems & Gemology Summer 1988

Inclusion

Stone

Reference

apatite

Gahnospinel

Zeitschrift der Deutschen Gemmologischen Gesellschaft, 1988,34, Nr3/4, p92-97