Scientists figure out origin of cobalt-blue spinel in Canada's Arctic

Small spinel stones with good transparency and fine cobalt-blue colour can sell for about 10 times the price of a comparable sapphire.

Spinel Color and Magnetism, Blue Spinel and Cobalt Spinel

Natural Color Change Cobalt Spinel 1.56 carats with AGTL Report / Jupitergem

GRS Alert: New spinel treatment discovered involving heat and cobalt-diffusion - GRS

Emerald-Cut Lab-Created Blue Sapphire and 1/20 CT. T.W. Diamond Frame Split Shank Ring in Sterling Silver

Minerals SpringerLink

This 1.39 ct near-colorless gem diamond (bottom left) has a complex

Spinel Color and Magnetism, Blue Spinel and Cobalt Spinel

Beware: Laser Damage in Sapphires due to Jewellery Repair - SSEF

Beluga calc-silicate rock under shortwave ultraviolet light showing the

Spinel - Wikiwand