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  GEMSTONES   

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

   These are the first sections to be uploaded and additional gems will be inserted in them as we proceed

 

 

Diffraction Spectra of 

Peridot

Colour Properties of Peridot

Colour

Yellowish green to brownish green

Cause of colour

Ferrous iron

Optical Character

Biaxial positive

Pleochroism

very weak – two shades of green

Colour change

No

Spectrum; no polar Calibration in nm.

Three evenly spaced weak narrow bands at 453; 573 and 493; Darker stones may show a weak diffuse bands at 529 and 635. 

Ordinary ray

Not applicable

Extraordinary ray

Not applicable

Alpha ray

493 extends to 495 and other two main bands are very weak

Beta ray

Three main bands are present but weak

Gamma ray

Three main bands are stronger and 493 extends to 497; Bands at 529 and 635 are more likely to be seen in this direction.

Emission lines

No

Database reference

None yet

Notes

Use a polarizing filter to locate gamma and intensify the three bands

Copyright John S. Harris 2000-2010

 

SPECTRA OF PRINCIPAL COMMERCIAL GEMSTONES

ALEXANDRITE

ALMANDINE GARNET

CHRYSOBERYL

DIAMOND

EMERALD

GREEN JADEITE

RUBY

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.