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Dichroscope

Pleochroism or selective absorbtion

Trichroism in a tanzanite

In uniaxial coloured stone, dichroism is possible, in bi axial stone, trichroism is possible, if absorbtion is identical no pleochroism

Dichroism in a cordierite

Dichroscope principle

Doubling

Trichroism in a tanzanite

how to use a dichroscope

For more information, visit: http://www.geminterest.com

Dichroism in a cordierite

For more information: visit www.gemologyproject.com

and the video here:

Doubling

Doubling in Mossanite and Zircon

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