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  GEMSTONE  SPECTRA    COMPARISON 

 GEMSTONE   COMPARISON DATABASE  

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

CHRYSOBERYL

DIAMOND

     EMERALD     

GREEN JADEITE

PERIDOT

RUBY

RED SPINEL

SAPPHIRE

SYN. BLUE SPINEL  & Co. GLASS

SYN. COLOUR CHANGE CORUNDUM

ZIRCON (Low type)

Other pages are under construction.

 

Diffraction Spectra of

 Zircon (high type)

Colour Properties of Zircon (Hightype)

Colour

Many colours in various hues often with brownish overtones. Rarely pale blue or colourless. Heat treated stones – Bright pale blue, orange or colourless.

Cause of  Colour

Uranium and Thorium.

Optical Character

 Uniaxial positive.

Pleochroism

 Mostly noticeable to very weak but strong in heat treated blue stones, the o-ray being the deeper shade of colour.

Colour change

No

Spectrum; no polar, calibration in nm.

High type - 691; 683; 662/660; 653; 621; 615; 589; 562; 537; 516; 511;484; 460. Dominant 653 is diagnostic, stronger lines underlined, others weak. Heat treated blue and colourless 653 and 660 possibly others but generally faint.

Ordinary ray

As no polar; but 662;653 and 516 are stronger. Lines at 621 and 615 are missing. Heat treated stones -  any visible lines stronger.

Extraordinary ray

As no polar; but 683;662/660; and 515 are stronger. Lines at 621 and 615 are present. Heat treated stones – Little or no change.

Alpha ray

Not applicable

Beta ray

Not applicable

Gamma ray

Not applicable

Emission lines

No

Database reference

None yet

Notes

Myanmar stones - Strong dark lines. Sri Lankan - Narrower lines but sharp.

 

Copyright John S. Harris 2000-2010