In the world of fine gems, few stones remain truly under the radar for long. Cobalt spinel is one of them. While collectors and investors have long been familiar with the prestige of sapphire, ruby, and emerald (the Big Three), cobalt-bearing spinel is gaining quiet momentum as one of the most desirable, naturally occurring blue gems in today’s market. Its vivid, velvety blue color rivals that of fine Kashmir sapphires, but unlike most sapphire, cobalt spinel is untreated, rare, and often sourced from politically sensitive areas in extremely small quantities.