Colour

Green, dark green to brownish green

Cause of colour

Chromium

Optical Character

Biaxial Positive        

Pleochroism

Red, orange and green in various hues according to lighting.

Colour change

Green in daylight, red in tungsten, distinct to weak in variable hues.

Spectrum; no polar Calibration in nm.

Absorption to up to 470. Broad absorption centred at 595. Lines in orange at 645;649;655;665; Doublet in red at 678/680.

Ordinary ray

Not applicable

Extraordinary ray

Not applicable

Alpha ray           Red

Absorbs up to 460. Line at 472;  Narrower absorption shifts towards short wave centred at 577;  649 & 665 missing. Others weak.

Beta ray       Orange

Absorbs up to 480. Mainly a weak band in the yellow/green at 570

Gamma ray    Green

Absorbs up to 470. Broader absorption shifts towards long wave  centred at 595 obscuring some lines in orange.  655 & 680 stronger.  

Emission lines

Seldom seen but visible in some synthetics at 678/680

Database reference

None yet

Notes

A variety of chrysoberyl.. Line at 472 seen in chromium rich stones