Colour

Yellowish green to brownish green

Cause of colour

Ferrous iron

Optical Character

Biaxial positive

Pleochroism

Pale shades of green, yellowish green and brownish green – weak!

Colour change

No

Spectrum; no polar Calibration in nm.

Three evenly spaced weak narrow bands at 453; 573 and 495; Darker stones may show a weak diffuse bands at 529 and 635. 

Ordinary ray

Not applicable

Extraordinary ray

Not applicable

Alpha ray

Pale green; Three main bands are present but weak.. 453 is broadest

Beta ray

Yellowish green;493 extends to 497 with some transmission between; the 473 and 453 strengthen.. A weak 529 may be detected.

Gamma ray

Brownish green Three main bands are stronger and 493 extends to 495;

Emission lines

No

Database reference

GN2 - Yellowish green gems

Notes

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