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 GEMSTONE SPECTRA

(EXCEL FILES)

   COLOURLESS STONES

 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

ORANGE STONES

OR1

YELLOW STONES

YL1

GREEN STONES

GN1 Green

GN2 Yellowish and greyish green

GN3 Bluish green

 GN4 Dark and brownish green

BROWN STONES

BN1 Light brown

BN2 Dark brown

BLUE STONES

BL1 Blue

BL2 Greenish blue

BL3 Lavender and indigo blue

VIOLET AND PURPLE STONES

VT - PL Violet and Purple

 Periodically other gemstones will be added to these files

 

 

Diffraction spectra of zircon (low type)

See my  DECLARATION OF COPYRIGHT

Colour Properties of Zircon (Low type)

Colour

Yellowish green, bright green or brownish green

Cause of  Colour

Uranium, Thorium and mainly radiation damage.

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

See Excel files on green gems

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 2000-2016

 

SPECTRA OF PRINCIPAL  COMMERCIAL GEMSTONES

ALEXANDRITE

ALMANDINE GARNET

CHRYSOBERYL

DIAMOND

EMERALD

GREEN JADEITE

PERIDOT

RUBY

BLUE SAPPHIRE  

RED SPINEL

GREEN & BLUE SPINEL

SYN. BLUE SPINEL  & Co. GLASS

SYN. COLOUR CHANGE CORUNDUM

ZIRCON (High type)

Other pages are under construction.

COLOUR FILTERS

 (EXCEL FILES)    

CF1 Basic Colour Filters

CF2 Special Colour Filters

EDUCATIONAL C. D.

  A GUIDE TO THE   SPECTROSCOPE