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INVESTIGATIONS

Stone

RI min

RI max

Biref min

Biref max

Dens min

Dens max

Colour

Location

Info

ne min

ne max

no min

no max

Spectrum

UVS

UVL

Reference

Taaffeite

1.715

1.729

0.004

0.006

3.6

3.69

light purple, purplish violet, violet, greyish violet, bluish violet, bluish grey

Tanzania, Africa

 

1.715

1.723

1.719

1.729

 

inert

inert

The Journal of Gemmology 2007 Nr 7/8, p367-382

Taaffeite

1.716

1.728

0.004

0.006

3.61

3.67

purple to purplish red

Sri Lanka and Birma

Cr-bearing taaffeites, small shift of colour between day and incandescent light

1.716

1.720

1.722

1.728

Cr and Fe

 

 

Gems & Gemology 2000 spring, p50-59

Taaffeite

1.716

1.719

0.003

0.003

3.64

3.64

pinkish

Sri Lanka

0.34ct

 

 

 

 

 

inert

inert

ACAM lab  2280

Taaffeite

1.716

1.721

0.004

0.004

3.6

3.61

very pale purplish pink (some iron-stained)

Mogok, Myanmar

1.33 - 5.16ct

1.716

1.717

1.720

1.721

 

inert

weak chalky green or white

The Journal of Gemmology 2014 Vol 34, No.2, p144-148

Taaffeite

1.717

1.727

0.004

0.005

3.62

3.66

greyish violet, purplish red

Sri Lanka

 

1.717

1.722

1.721

1.727

 

 

 

The Australian Gemmologist 2006 jul-sep, p486

Taaffeite

1.717

1.723

0.004

0.006

3.6

3.62

 

Elahera, Sri Lanka

 

 

 

 

 

 

inert

inert

Gems & Gemology 1986 Summer, p91

Taaffeite

1.717

1.123

0.004

0.005

3.6

3.61

mauve

 

2 stones, dispersion (B-G): 0.019

1.717

1.718

1.721

1.723

 

 

 

Gems & Gemology 1968 Spring, p259

Taaffeite

1.718

1.722

0.004

0.004

3.6

3.6

red

 

0.58ct

 

 

 

 

emission line around 684nm

 

 

Zeitschrift der Deutschen Gemmologischen Gesellschaft 1991 Apr, p33-37

Taaffeite

1.718

1.724

0.006

0.006

3.67

3.67

bluish, smoky grey in daylight

 

0.70 ct

 

 

 

 

 

 

 

The Journal of Gemmology 1986 Vol20, N°3, p151

Taaffeite

1.718

1.722

0.004

0.004

3.59

3.59

sapphir blue

 

3.34 ct

 

 

 

 

 

 

 

Gems & Gemology 1980 Spring, p268

Taaffeite

1.718

1.721

0.003

0.003

3.63

3.63

 

Sri Lanka

1.09ct

 

 

 

 

 

inert

inert

The Journal of Gemmology 2014 Vol 34, No.2, p146

Taaffeite

1.72

1.724

0.004

0.004

3.61

3.61

colour canging from bluish to reddish

Sri Lanka

12.23ct

 

 

 

 

 

 

 

Zeitschrift der Deutschen Gemmologischen Gesellschaft 1989 Aug, p89-94

Taaffeite

1.72

1.724

0.004

0.004

3.63

3.63

violetish blue

Sri Lanka

3.23ct

 

 

 

 

lines at 465, 480nm

inert

inert

GIA Gem Database  34196

Taaffeite

1.72

1.726

0.006

0.006

3.63

3.63

purplish red

Sri Lanka

11.23ct

 

 

 

 

lines at 466, 482nm

inert

inert

GIA Gem Database  34183

Taaffeite

1.72

1.72

 

 

3.68

3.68

purplish brown

 

1.44ct, cabochon, cat's-eye, spot RI, reflective planar inclusions with striations

 

 

 

 

 

inert

inert

Gems & Gemology 1999 spring p 46

Taaffeite

1.721

1.727

0.006

0.006

3.63

3.63

bluish to reddish colour-changing

Sri Lanka

2.82ct

 

 

 

 

intensive 555nm and 463nm, additional 624, 470, 415, 402nm

 

 

Gemmologie, Zeitschrift der Deutschen Gemmologischen Gesellschaft 2000 Mar, p1

Taaffeite

1.721

1.726

0.005

0.005

3.62

3.62

purplish red

Sri Lanka

1.23ct

 

 

 

 

broad absorption below 425nm

inert

weak red

GIA Gem Database  34186

Taaffeite

1.721

1.726

0.005

0.005

3.61

3.61

purplish red

Sri Lanka

2.26ct

 

 

 

 

line at 466nm

inert

inert

GIA Gem Database  34188

Zn-Taaffeite

1.724

1.735

0.004

0.006

3.69

3.78

 

Ratnapura, Sri Lanka

 

1.724

1.730

1.729

1.735

 

 

 

The Journal of Gemmology 2005 29, 5/6, p290-298

Zn-Taaffeite

1.726

1.73

0.004

0.004

3.71

3.71

reddish violet

Sri Lanka

 

1.726

1.726

1.730

1.730

 

 

 

Zeitschrift der Deutschen Gemmologischen Gesellschaft 1985 34, Nr 1/2, p20-23

Zn-Taaffeite

1.726

1.73

0.004

0.004

3.71

3.71

reddish violet

Sri Lanka

1.25ct

 

 

 

 

 

 

 

The Journal of Gemmology 1985 Vol 19, No 6, p494-497

Taaffeite

1.73

 

 

 

3.6

3.6

purplish red

Myanmar

6.23ct

 

 

 

 

 

inert

inert

GIA Gem Database  34665

Taaffeite

 

 

 

 

 

 

brownish grey

 

0.61ct

 

 

 

 

 

inert

inert

Gems & Gemology 1987 Fall, p168

 

TABLES

Stone

RI min

RI max

Biref min

Biref max

Dens min

Dens max

ne min

ne max

no min

no max

Reference

Taaffeite

1.715

1.747

0.004

0.009

3.6

3.7

1.715

1.741

1.721

1.747

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

Taaffeite

1.716

1.73

0.004

0.004

3.59

3.72

1.716

1.726

1.720

1.730

Gemmological Tables, Ulrich Henn, 2004 

Taaffeite

1.716

1.725

0.003

0.007

3.58

3.64

 

 

 

 

Gemmo.eu 

Taaffeite

1.717

1.73

0.004

0.009

3.6

3.71

 

 

 

 

http://www.gemmology.be 

Taaffeite

1.717

1.723

0.003

0.004

36

3.61

1.717

1.722

1.718

1.723

Tabellen zur Edelstein-Bestimmung, Pschichholz FGA, 1975 

Taaffeite

1.717

1.735

0.004

0.009

3.6

3.71

1.717

1.726

1.721

1.735

Joel Arem, Color Encyclopedia of Gemstones, 1987 

Taaffeite

1.717

1.747

0.003

0.009

3.59

3.71

1.717

1.741

1.721

1.747

http://www.geminterest.com 

Taaffeite

1.717

1.724

0.004

0.009

3.6

3.62

1.717

1.720

1.721

1.724

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

Taaffeite

1.718

1.722

0.004

0.004

3.6

3.61

 

 

 

 

John Sinkakas, Gemstone and mineral data book,1972 

Taaffeite

1.718

1.722

0.004

0.004

3.6

3.61

 

 

 

 

Gems, R Webster, 5th edition 1994 

Taaffeite

1.719

1.747

0.004

0.009

3.59

3.67

 

 

 

 

Bestimmungstabellen für Edelsteine, Birgit Günther, 2008 

Taaffeite

1.719

1.725

0.004

0.005

3.6

3.62

 

 

 

 

Gemology Tools Professional 2010

Zn-Taaffeite

1.724

1.735

0.004

0.006

3.69

3.78

 

 

 

 

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

 

CAUSE OF COLOUR

Stone

Colour

Cause of colour

Reference

Taaffeite

red to violet

Cr³+ in octahedral coordination

Gems & Gemology Summer 1988

 

MINERAL INCLUSIONS

Inclusion

Stone

Reference

apatite

Taaffeite

E.J. Gübelin and J.I. Koivula, Photoatlas of inclusions in Gemstones, volume 2 (2005)

magnesite

Taaffeite

Gems & Gemology 2000 spring p54

muscovite

Taaffeite

Gems & Gemology 1984 Fall p161

phlogopite

Taaffeite

Gems & Gemology 1986 Summer p91

spinel

Taaffeite

Gems & Gemology 1986 Summer p91

zircon

Taaffeite

Gems & Gemology 2000 spring p54

 

LOCALITIES

STONE

LOCALITIES

REFERENCE

Taaffeite

 

Elehara

 

Sri Lanka

Gems & Gemology 1986 Summer, p91

 

CHEMICAL DATA (%)

Stone

Colour

Locality

Reference

Al2O3

MnO

MgO

FeO

TiO2

Cr2O3

V2O3

Ga2O3

ZnO

BeO

Taaffeite

greyish violet

 

Myanmar

Gems & Gemology 2000 Spring p52

72.14

0.02

21.58

0.8

0.01

0.01

0.01

0.05

0.09

4.45

Taaffeite

dark purplish violet

Delwela

Sri Lanka

The Journal of Gemmology 2005, 29, 5/6, 290-298

70.58

0.05

17.74

5.62

0.03

0.02

 

 

0.82

4.35

Taaffeite

greyish violet

Mudunkotuwa

Sri Lanka

The Journal of Gemmology 2005, 29, 5/6, 290-298

70.13

0.06

15.63

1.76

0.01

0.01

0.02

 

8.87

4.31

Taaffeite

light violet

 

Sri Lanka

The Journal of Gemmology 2005, 29, 5/6, 290-298

71.05

0.04

17.8

1.4

0.01

0.01

0.01

 

5.27

4.36

Taaffeite

reddish violet

 

Sri Lanka

The Journal of Gemmology 2005, 29, 5/6, 290-298

71.1

0.06

17.69

1.88

 

0.15

 

 

4.66

4.37

Zn-Taaffeite

 

 

Sri Lanka

Zeitschrift der Deutschen Gemmologischen Gesellschaft, 1985, 34, Nr1/2, p22

71.1

0.06

17.69

1.88

 

0.15

 

 

4.66

4.4

Taaffeite

greyish violet

 

Sri Lanka

Gems & Gemology 2000 Spring p52

72.12

0.02

20.92

2.1

0.01

0.01

0.01

0.04

0.11

4.46

Taaffeite

purple

 

Sri Lanka

Gems & Gemology 2000 Spring p52

72.77

0.03

20.98

1.89

0.01

0.1

0.01

0.04

0.05

4.49

Taaffeite

purple

 

Sri Lanka

Gems & Gemology 2000 Spring p52

72.62

0.04

19.4

2.21

0.01

0.11

0.01

0.03

0.59

4.43

Taaffeite

reddish purple

 

Sri Lanka

Gems & Gemology 2000 Spring p52

71.12

0.03

19.71

2.05

0.02

0.14

0.02

0.04

2.11

4.4

Taaffeite

reddish purple

 

Sri Lanka

Gems & Gemology 2000 Spring p52

72.9

0.04

20.52

1.37

0.01

0.13

0.01

0.03

0.09

4.46

Taaffeite

reddish purple

 

Sri Lanka

Gems & Gemology 2000 Spring p52

72.62

0.02

20.73

1.54

0.01

0.13

0.01

0.02

0.55

4.47

Taaffeite

purplish red

 

Sri Lanka

Gems & Gemology 2000 Spring p52

72.13

0.03

20.15

1.52

0.01

0.21

0.02

0.05

1.18

4.44

Taaffeite

purplish red

 

Sri Lanka

Gems & Gemology 2000 Spring p52

71.88

0.03

19.71

2.59

0.02

0.18

0.01

0.04

0.38

4.42

Taaffeite

purplish red

 

Sri Lanka

Gems & Gemology 2000 Spring p52

71.31

0.06

18.85

2.09

0.02

0.33

0.04

0.02

2.24

4.39

Taaffeite

colour changing bluish to reddish

 

Sri Lanka

Zeitschrift der Deutschen Gemmologischen Gesellschaft 1989, Aug, p90

73.33

0.001

20.43

1.82

 

0.03

 

0.05

0.11

 

Taaffeite

 

 

Tanzania

The Journal of Gemmology 2007, 30, 7/8, p 372

73.02

0.03

20.11

1.38

0.01

0.01

0.01

 

0.12

4.47