Gemlab.UK  Gemmological Spectroscopy      SYN. COLOUR CHG. CORUNDUM

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GEMSTONE SPECTRA

(EXCEL FILES)

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 synthetic colour change corundum

See my  DECLARATION OF COPYRIGHT

 

Colour Properties of Synthetic colour Change Corundum

Colour

Greyish  blue with a purple overtone and red flashes

Cause of colour

Vanadium. Chromium may also be present.

Optical Character

Uniaxial negative     

Pleochroism

Daylight;  ω -  Pale purplish blue; ε - Pale greyish green            Tungsten; ω -  Pale purplish pink; ε Pale orangy yellow; 

Colour change

Greyish blue in daylight to strong purplish red in tungsten light

Spectrum; no polar, calibration in nm.

Absorption band in green centred at 570. is responsible for colour change and dichroism Narrow line at 475 in blue due to vanadium.

Ordinary ray

Absorption band in green strengthens and widens.Fluorescent lines may be seen in red due to chromium.

Extraordinary ray

Absorption band in green weaker and narrower.

Alpha ray

Not applicable

Beta ray

Not applicable

Gamma ray

Not applicable

Emission lines

Fluorescent doublet may be seen at 693/694nm. if  Cr. is  present

Database reference

Blue Gems. Excel file BL3

Notes

Compare to alexandrite

 

Copyright John S. Harris 2000-2016

 

SPECTRA OF

 PRINCIPAL 

COMMERCIAL GEMS

ALEXANDRITE

ALMANDINE GARNET

CHRYSOBERYL

DIAMOND

EMERALD

GREEN JADEITE

PERIDOT

RUBY

BLUE SAPPHIRE  

RED SPINEL

GREEN & BLUE SPINEL

SYN.  BLUE SPINEL  & Co. GLASS

ZIRCON (High type)

ZIRCON (Low 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