cobalt spinel
Spinel is one of the birthstones for August.
Among spinels, those that contain a large amount of cobalt and exhibit a bright blue color are called cobalt spinels.
The shade of blue is thought to change depending on the cobalt content, and the darker the blue, the more valuable it is.
Karatz GemMagazine
" Cobalt Spinel "
Karatz GemMagazine
" Cobalt Spinel "