Faceted Blue Spinel Gemstones, Soviet Gem

These are blue gems cut from old stock flame fusion spinel grown in the Soviet Union,  sourced from an old collection  The color intensity and darkness varies considerably from stone to stone, each is photographed individually.

Blue Spinel is typically colored by cobalt, which gives it a red fluorescence with strengh varying based on cobalt concentration and codopant types.

While this material is grown with the flame fusion method, in industry Czochralski-pulled cobalt spinel can be grown to ultra high purities and used in lasers as a Q switch, but this material was grown purely for use in the gem trade. This color of spinel is sometimes found in nature as a very rare and prized gemstone, but it is never available in large sizes.