Gemlab.UK  Gemmological Research and Education    

                              HOME           EDUCATION        SPECTROSCOPY       SPECTRA DATABASE        NEWS

 

  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

GREEN JADEITE

PERIDOT

RUBY

RED SPINEL

SAPPHIRE

SYN. BLUE SPINEL  & Co. GLASS

SYN. COLOUR CHANGE CORUNDUM

ZIRCON (High type)

ZIRCON (Low type)

Other pages are under construction.

 

Diffraction Spectra  of

Emerald

Colour Properties of  Emerald

Colour

Green, yellowish green, bluish green.

Cause of colour

Chromium

Optical Character

Uniaxial negative

Pleochroism

Distinct; Two shades of green, o ray – green, e ray – bluish green

Colour change

No

Spectrum; no polar Calibration in nm.

Violet absorbed. Broad band over orange & yellow/green, moderate line at 637.weak lines at 646 & 662. Doublet at 680/683.

Ordinary ray

As above plus a weak narrow line at 477 in Cr. rich stones. The broad band becomes narrower to reveal a stronger 637 line and the lines at 646 & 662 are missing. The doublet is weaker.

Extraordinary ray

Violet absorbed. The broad band widens to obscure the lines at 637 & 642. The 662 strengthens. The 683 in the doublet is the stronger.

Alpha ray

Not applicable

Beta ray

Not applicable

Gamma ray

Not applicable

Emission lines

No

Database reference

None yet

Notes

The broad band is faint and lines weaker in pale coloured stones

 

 

 

Copyright John S. Harris 2000-2010