7MM Cobalt COMFORT FIT Plain High Polish Polished Finish Wedding Ring Band for Men (Sizes 8 to 12) 4X Harder than Platinum, 5X Harder than Gold, and 7X Harder than Silver. Same Color as Brilliant Platinum Cobalt is the Ultimate Contemporary Metal. Perfect for those who love the color of Platinum or White Gold Hypoallergenic, scratch resistant and biocompatible. This metal will NOT cause ANY allergic reactions, or redness to the skin Cobalt... unlike Tungsten is shatter proof. All Cobalt Rings purchased from Jewelry Vortex will include FREE-SHIPPING