|
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 |
Sillimanite |
1.577 |
1.587 |
0.017 |
0.018 |
3.26 |
3.26 |
yellow-green, greenish yellow |
India |
49.29, 25.05, and 21.12 ct |
1.58 |
1.58 |
|
|
1.58 |
1.59 |
strong absorption band at 460 nm |
inert |
inert |
Gems & Gemology 2006 Spring, p66-67 |
Sillimanite |
1.65 |
1.67 |
0.02 |
0.02 |
3.25 |
3.25 |
blue |
Eheliyagoda, Sri Lanka |
18.86ct |
|
|
|
|
|
|
no features |
inert |
inert |
GIA Gem Database 34916 |
Sillimanite |
1.654 |
1.673 |
0.019 |
0.019 |
3.28 |
3.28 |
bluish violet |
Mogok, Myanmar |
11.79ct |
|
|
|
|
|
|
|
inert |
inert |
GIA Gem Database 34535 |
Sillimanite |
1.655 |
1.675 |
0.02 |
0.02 |
3.26 |
3.26 |
colourless |
Sri Lanka |
0.94ct |
1.655 |
1.655 |
1.659 |
1.659 |
1.675 |
1.675 |
none |
weak pinkish violet |
weak violet |
ACAM Lab
2294 |
Sillimanite |
1.655 |
1.675 |
0.02 |
0.02 |
3.26 |
3.26 |
light violetish blue |
Kolonne, Sri Lanka |
12.03ct |
|
|
|
|
|
|
no features |
inert |
inert |
GIA Gem Database 34887 |
Sillimanite |
1.656 |
1.675 |
0.019 |
0.019 |
3.25 |
3.25 |
light violet |
Eheliyagoda, Sabaragamuwa Province, Sri
Lanka |
2.62ct |
|
|
|
|
|
|
|
inert |
inert |
GIA Gem Database 34018 |
Sillimanite |
1.658 |
1.677 |
0.019 |
0.019 |
3.25 |
3.25 |
light blue, colourless to greyish |
sri Lanka |
|
|
|
|
|
|
|
|
|
|
The Australian Gemmologist 1987 may, p241 |
Sillimanite |
1.658 |
1.681 |
0.02 |
0.021 |
3.26 |
3.26 |
yellowish green to greenish yellow |
Orissa, India |
between 2.85 and 1063 cts |
1.66 |
1.660 |
|
|
1.679 |
1.681 |
|
|
|
Gemmologie, Zeitschrift der Deutschen
Gemmologischen Gesellschaft 2006 Jun p59-61 |
Sillimanite |
1.658 |
1.678 |
0.02 |
0.02 |
3.23 |
3.23 |
colourless |
Sri Lanka |
1.48ct |
|
|
|
|
|
|
|
|
|
Gemmologie, Zeitschrift der Deutschen
Gemmologischen Gesellschaft 1999 Jul p106 |
Sillimanite |
1.658 |
1.678 |
0.02 |
0.02 |
3.31 |
3.31 |
yellowish orange |
Mogok, Myanmar |
3.47ct |
|
|
|
|
|
|
|
inert |
inert |
GIA Gem Database 34014 |
Sillimanite |
1.658 |
1.678 |
0.02 |
0.02 |
3.38 |
3.38 |
light violet purplish |
Mogok, Myanmar |
11.16ct |
|
|
|
|
|
|
|
inert |
inert |
GIA Gem Database 34552 |
Sillimanite |
1.659 |
1.679 |
0.02 |
0.02 |
3.24 |
3.24 |
dyed red |
|
7 to 12 ct |
1.66 |
1.659 |
1.665 |
1.665 |
1.679 |
1.679 |
|
|
|
Gemmologie, Zeitschrift der Deutschen
Gemmologischen Gesellschaft 2005 Sep, p71-72 |
Sillimanite |
1.659 |
1.679 |
0.02 |
0.02 |
3.22 |
3.22 |
red (dyed) |
|
9.61 and 11.40ct, ruby imitation, biaxal +, dyed + impregnated, chelsea
filter: pink |
|
|
|
|
|
|
600 nm cut-off |
inert |
moderate red to long-wave with yellow emission |
Gems & Gemology 2005 Fall, p297 |
Sillimanite |
1.659 |
1.679 |
0.02 |
0.02 |
3.22 |
3.22 |
dyed red (to imitate ruby) |
|
|
|
|
|
|
|
|
|
inert with yellow emission along the fractures |
moderate red with yellow emission along the fractures, |
Gems & Gemology 2005 Fall, p274 |
Sillimanite |
1.66 |
1.682 |
0.022 |
0.022 |
3.25 |
3.25 |
|
Elahera, Sri Lanka |
|
1.66 |
1.660 |
1.662 |
1.662 |
1.682 |
1.682 |
4.62, 441, 410nm |
inert |
inert |
Gems & Gemology 1986 Summer, p91 |
Sillimanite |
1.66 |
1.682 |
0.022 |
0.022 |
3.3 |
3.3 |
light yellowish |
|
biaxial positive |
|
|
|
|
|
|
|
weak orange |
weak orange |
The Journal of Gemmology 1986 Vol20, N°3, p151 |
Sillimanite |
1.66 |
1.66 |
|
|
3.196 |
3.226 |
greyish green with cat's eye |
|
cat's eyes, 2 - 11.42 ct, almost opaque |
|
|
|
|
|
|
|
|
|
The Journal of Gemmology 1982 Vol18, N°4 p277-281 |
Sillimanite |
1.66 |
1.68 |
0.02 |
0.02 |
3.2 |
3.2 |
very dark brown |
|
3.44ct, cabochon, cat's-eye, spot RI |
|
|
|
|
|
|
general absorption up to about 490 nm, with a broad dark band
superimposed at 440 to 450 nm |
inert |
inert |
Gems & Gemology 1987 Fall, p167-168 |
Sillimanite |
1.661 |
1.68 |
0.019 |
0.019 |
3.26 |
3.26 |
light grey |
|
6.65 ct, resembling moonstone |
|
|
|
|
|
|
|
inert |
inert |
Gems & Gemology 2006 Summer, p179 |
Sillimanite |
|
|
|
|
3.25 |
3.25 |
green, brown, grey-violet |
Guinea |
cat's eyes, transparent to translucent, 1.99 to 4.79 ct |
|
|
|
|
|
|
|
|
|
Gemmologie, Zeitschrift der Deutschen
Gemmologischen Gesellschaft 2009 58/3-4/Dec, p81 |
Sillimanite |
|
|
|
|
|
|
green (dyed) |
|
to imitate emerald, 14.5-43.5ct |
|
|
|
|
|
|
|
|
|
Gems & Gemology 2009 Winter,
p308-309 |
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 |
Sillimanite |
1.652 |
1.685 |
0.016 |
0.023 |
3.2 |
3.3 |
|
|
|
|
|
|
Gemmo.eu
|
Sillimanite |
1.653 |
1.684 |
0.015 |
0.021 |
3.23 |
3.27 |
|
|
|
|
|
|
Gemology Tools Professional 2010 |
Sillimanite |
1.654 |
1.674 |
0.013 |
0.021 |
3.22 |
3.27 |
1.654 |
1.661 |
|
|
1.684 |
1.674 |
Gemme, Dati per l'identificazione, P. De
Stefano et al, 1993 |
Sillimanite |
1.654 |
1.683 |
0.02 |
0.02 |
3.14 |
3.27 |
|
|
|
|
|
|
http://www.gemmology.be |
Sillimanite |
1.654 |
1.683 |
0.02 |
0.02 |
3.23 |
3.27 |
1.654 |
1.661 |
1.658 |
1.662 |
1.673 |
1.683 |
Joel Arem, Color Encyclopedia of Gemstones,
1987 |
Sillimanite |
1.654 |
1.684 |
0.015 |
0.021 |
3.23 |
3.28 |
1.654 |
1.661 |
1.658 |
1.662 |
1.673 |
1.684 |
http://www.geminterest.com |
Sillimanite |
1.654 |
1.684 |
0.014 |
0.021 |
3.22 |
3.27 |
1.654 |
1.661 |
1.658 |
1.662 |
1.673 |
1.684 |
Tables of Gemstone Identification, Roger Dedeyne,
Ivo Quintens, 2007 |
Sillimanite |
1.655 |
1.684 |
0.014 |
0.021 |
3.22 |
3.26 |
1.655 |
1.661 |
|
|
1.677 |
1.684 |
Bestimmungstabellen für Edelsteine,
Birgit Günther, 1981 |
Sillimanite |
1.655 |
1.684 |
0.014 |
0.021 |
3.2 |
3.25 |
1.655 |
1.661 |
1.658 |
1.670 |
1.677 |
1.684 |
Gemmological Tables, Ulrich Henn,
2004 |
Sillimanite |
1.657 |
1.679 |
0.015 |
0.021 |
3.22 |
3.26 |
1.657 |
1.659 |
|
|
1.673 |
1.679 |
Tabellen zur Edelstein-Bestimmung,
Pschichholz FGA, 1975 |
CAUSE OF
COLOUR
Stone |
Colour |
Cause
of colour |
Reference |
Sillimanite |
blue |
Fe²+-O-Ti4+ charge transfer, simular to blue kyanite |
Gems & Gemology Summer 1988 |
Sillimanite |
yellow |
Fe³+ or Cr³+ in tetrahedral coordination |
Gems & Gemology Summer 1988 |
Sillimanite |
brown |
Fe features of yellow sillimanite plus inclusions of
iron-rich phase |
Gems & Gemology Summer 1988 |
MINERAL
INCLUSIONS
Inclusion |
Stone |
Reference |
apatite |
Sillimanite |
Gems & Gemology Summer 1986, p91 |
hematite |
Sillimanite |
The Journal of Gemmology 1982, Vol18, N°4 p277-281 |
magnetite |
Sillimanite |
The Journal of Gemmology 1982, Vol18, N°4 p277-281 |
rutile |
Sillimanite |
Gems & Gemology 2005 fall, p274 |
zircon |
Sillimanite |
Gems & Gemology Summer 1986, p91 |
LOCALITIES
STONE |
LOCALITIES |
REFERENCE |
|||
Sillimanite |
|
Orissa |
|
India |
Gemmologie jun 2006 p60 |
Sillimanite |
|
Vishakhapatnam |
Andhra Pradesh |
India |
Gems & Gemology 2006 spring p 67-68 |
Sillimanite |
Morawaka |
Deniyaya district |
|
Sri Lanka |
Gems & Gemology 1988 Spring p58 |
CHEMICAL DATA
(%)