SYNTHETIC BLUE SPINEL

COBALT BLUE GLASS

Colour

Pale to deep intense blue

Pale to deep intense blue

Cause of colour

Cobalt

Cobalt

Optical Character

Isotropic

Isotropic

Pleochroism

Not applicable

Not applicable

Colour change

No

No

Spectrum; no polar, calibration in nm.

Three broad bands centred at 540;580;(Broadest) and 635:

Three broad bands centred at       535; 590 (Narrowest) and 655:

Ordinary ray

Not applicable

Not applicable

Extraordinary ray

Not applicable

Not applicable

Alpha ray

Not applicable

Not applicable

Beta ray

Not applicable

Not applicable

Gamma ray

Not applicable

Not applicable

Emission lines

No

No

Database reference

BL1;

BL1; BL3

Notes

Pale stones show weak vague bands, only one in red may be seen in some stones.