GEMSTONE SPECTRA COMPARISON
These are the first sections to be
uploaded and additional gems will be inserted in them 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
PERIDOT
RUBY
RED SPINEL
SAPPHIRE
SYN. BLUE SPINEL
& Co. GLASS
SYN. COLOUR CHANGE CORUNDUM
ZIRCON (High type)
Other pages are under construction. |
Diffraction Spectra
of
Zircon (Low type)

Colour Properties
of Zircon (Low type)
|
Colour |
Yellowish green, bright green or brownish green |
|
Cause of
Colour |
Uranium and Thorium. |
|
Optical Character |
Low type metamicts may show a biaxial figure as they revert to a
monoclinic structure or be almost amorphous, showing interference
colours due to strain in crossed polars. |
|
Pleochroism |
None generally detected |
|
Colour change |
No |
|
Spectrum; no polar, calibration in nm. |
Diffuse and vague absorption bands at 660 and 520. Low type
with anomalous spectrum (This may be a natural or heat treated
metamict) – Three distinctive strong bands appear in the red instead
of the usual single broad vague band. Other bands may be present. |
|
Ordinary ray |
Little or no change to spectrum. |
|
Extraordinary ray |
Little or no change to spectrum |
|
Alpha ray |
Not applicable |
|
Beta ray |
Not applicable |
|
Gamma ray |
Not applicable |
|
Emission lines |
No |
|
Database reference |
None yet |
|
Notes |
Many metamict zircons are from Sri Lanka. R.I. may be as low as
1.788 with little or no birefringence. Intermediate varieties,
natural or heat treated, have a higher SG and RI as their
crystalline structure is restored and may show an anomalous spectrum |
Copyright John S.
Harris
2000-2010 |