Gemlab.UK  Gemmological Spectroscopy     EMERALD

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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

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

 

Emerald

See my  DECLARATION OF COPYRIGHT

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

GN1 and GN3

Notes

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

 

 

 

 

Copyright John S. Harris 2000-2016

 

SPECTRA OF

 PRINCIPAL 

COMMERCIAL GEMS

ALEXANDRITE

ALMANDINE GARNET

CHRYSOBERYL

DIAMOND

GREEN JADEITE

PERIDOT

RUBY

BLUE SAPPHIRE

RED SPINEL

GREEN & BLUE SPINEL

SYN. BLUE SPINEL  & Co. GLASS

SYN. COLOUR CHANGE CORUNDUM

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