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INVESTIGATIONS

Stone

RI min

RI max

Biref min

Biref max

Dens min

Dens max

Colour

Locality

Info

nx min

nx max

ny min

ny max

nz min

nz max

Spectrum

UVS

UVL

Reference

Grandidierite

1.568

1.67

0.035

0.05

2.88

2.92

light bluish green to intense bluish green

Madagascar

 6 samples are rough materials weighing from 0.41-1.24 cts

 

 

 

 

 

 

 

inert

inert

https://www.git.or.th 2017 30 Mar

Grandidierite

1.579

1.62

0.041

0.041

2.91

2.91

greyish blue-green

Madagascar

 

 

 

 

 

 

 

Faint absorption line in the blue spectrum around 470-490 nm

 

 

Gems & Gemology 2015 Winter, p449

Grandidierite

1.58

1.62

0.04

0.04

2.94

2.94

greyish blue-green

 

1.79ct

1.580

1.580

1.605

1.605

1.620

1.620

 

 

 

ACAM lab  4610

Grandidierite

1.58

1.63

0.04

0.04

3.04

3.04

greenish blue

Madagascar

0.31ct

 

 

 

 

 

 

faint line / absorption at around 470 nm

 

 

http://gtljaipur.info/ProjectUpload/labDownLoad/LIC%2074%20_June2017.pdf  

Grandidierite

1.583

1.622

0.039

0.039

2.96

2.96

greenish blue

Sri Lanka

1 stone, transparent

1.583

1.583

1.620

1.620

1.622

1.622

line at 479nm

inert

inert

Gems & Gemology 2003 spring, p32-37

Grandidierite

1.583

1.622

0.039

0.039

2.85

2.85

slatey blue, translucent

 

 

 

 

 

 

 

 

 

 

 

The Journal of Gemmology 1977 N°7, p357-358

Grandidierite

1.59

1.639

0.033

0.033

3

3

blue-green

Andrahomana, Madagascar

 

1.590

1.590

1.618

1.618

1.623

1.623

 

 

 

Gemmologie, Zeitschrift der Deutschen Gemmologischen Gesellschaft 2000 Sep, p121

Grandidierite

 

 

 

 

2.99

3.03

bluish green to greenish blue

Tranomaro area, Departementa Amboasary, Anosy, Toliara Province, Madagascar

 

 

 

 

 

 

 

 

inert

inert

Gems & Gemology 2016 Fall, p 266-275

 

TABLES

Stone

RI min

RI max

Biref min

Biref max

Dens min

Dens max

nx min

 nx max

ny min

ny max

nz min

nz max

Reference

Grandidierite

1.577

1.625

0.036

0.042

2.9

3

 

 

 

 

 

 

Gemmo.eu 

Grandidierite

1.583

1.639

0.039

0.039

2.85

3

1.583

1.602

1.618

1.636

1.622

1.639

Joel Arem, Color Encyclopedia of Gemstones, 1987 

Grandidierite

1.583

1.639

0.037

0.039

2.85

3

1.583

1.602

 

 

1.622

1.639

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

Grandidierite

1.583

1.6

0.037

0.039

2.85

3

1.583

1.602

1.620

1.636

1.622

1.600

Gemmological Tables, Ulrich Henn, 2004 

Grandidierite

1.583

1.639

0.039

0.039

2.85

3

 

 

 

 

 

 

http://www.gemmology.be 

Grandidierite

1.583

1.639

0.039

0.039

2.85

3

1.583

1.602

1.618

1.636

1.622

1.639

http://www.geminterest.com 

Grandidierite

1.583

1.629

0.039

0.039

2.85

3

1.583

1.602

1.618

1.636

1.622

1.629

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

Grandidierite

1.583

1.639

0.039

0.039

2.85

3

 

 

 

 

 

 

Gemology Tools Professional 2010

Grandidierite

1.602

1.639

0.037

0.037

3

3

 

 

 

 

 

 

Bestimmungstabellen für Edelsteine, Birgit Günther, 1981 

Grandidierite

1.602

1.639

0.037

0.039

3

3

 

 

 

 

 

 

Tabellen zur Edelstein-Bestimmung, Pschichholz FGA, 1975 

Grandidierite

1.602

1.639

0.037

0.037

3

3

 

 

 

 

 

 

Gems, R Webster, 5th edition 1994 

 

CAUSE OF COLOUR

Stone

Colour

Cause of colour

Reference

Grandidierite

blue

Fe²+ ion and its interaction with Fe³+

http://minerals.caltech.edu

 

MINERAL INCLUSIONS

 

LOCALITIES

STONE

LOCALITIES

REFERENCE

Grandidierite

Cap Andrahomana, Departementa Ranopiso

Anosy (Fort Dauphin Region)

Toliara (Tuléar) Province

Madagascar

Michael O'Donoghue, Gems: Their Sources, Descriptions and Identification (2006),  873pp

Grandidierite

Tranomaro area, Departementa Amboasary

Anosy (Fort Dauphin Region)

Toliara (Tuléar) Province

Madagascar

Gems & Gemology 2016 Fall p266-275

 

CHEMICAL DATA

Stone

Colour

Locality

Reference

SiO2

Al2O3

MnO

MgO

FeO

TiO2

CaO

Cr2O3

Fe2O3

B2O3

Grandidierite

 

 

Sri Lanka

Gems & Gemology 2003 Spring p34

20.2

52.64

0.03

12.85

1.31

0.01

0.01

0.07

0.01

11.91

Grandidierite

 

 

Madagascar

Gems & Gemology 2015 Winter, p450

16.41

53.89

0.01

17.01

0.3

 

 

0.01

 

12.33

Grandidierite

 

southern Madagascar

Madagascar

Gems & Gemology 2016 Fall, p 272

20.25

53.17

 

14.28

0.52

 

 

 

 

10.38