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GEMSTONE SPECTRA COMPARISON
These are the first sections to be uploaded and additional
gems will be inserted in them as we proceed
COLOURLESS
STONES
CS1
RED STONES
RD1
Dark red
RD2 Pinkish red
RD3
Orangy red
RD4 Slightly purplish red
RD5 Purplish red
PINK STONES
PK1 Lilac pink
PK2 Pink and orangy pink
PK3
Brownish and purplish pink
SPECTRA OF PRINCIPAL GEMSTONES
ALEXANDRITE
ALMANDINE
GARNET
CHRYSOBERYL
DIAMOND
EMERALD
GREEN JADEITE
RUBY
RED SPINEL
SAPPHIRE
SYN. BLUE SPINEL
& Co. GLASS
SYN. COLOUR CHANGE CORUNDUM
ZIRCON (High type)
ZIRCON (Low type)
Other pages are under construction.
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Diffraction Spectra
of
Peridot

Colour Properties
of Peridot
|
Colour |
Yellowish green to brownish green |
|
Cause of colour |
Ferrous iron |
|
Optical Character |
Biaxial positive |
|
Pleochroism |
very weak – two shades of green |
|
Colour change |
No |
|
Spectrum; no polar Calibration in nm. |
Three evenly spaced weak narrow bands at 453; 573 and 493; Darker
stones may show a weak diffuse bands at 529 and 635.
|
|
Ordinary ray |
Not applicable |
|
Extraordinary ray |
Not applicable |
|
Alpha ray |
493 extends to 495 and other two main bands are very weak |
|
Beta ray |
Three main bands are present but weak |
|
Gamma ray |
Three main bands are stronger and 493 extends to 497; Bands at 529
and 635 are more likely to be seen in this direction. |
|
Emission lines |
No |
|
Database reference |
None yet |
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Notes |
Use a polarizing filter to locate gamma and intensify the three
bands |
Copyright John S.
Harris
2000-2010 |