Cobalt is a hard and lustrous metal. Pure cobalt is not found in nature, but compounds of cobalt are common. Cobalt is the whitest contemporary material offered today. Cobalt rings resemble and have the look and feel of White Gold or Platinum rings. Cobalt Rings stay as white and never need any rhodium plating. Cobalt is hypoallergenic. Although Cobalt may scratch, they could be polished like platinum or white gold.