This Domed Satin 4MM Wedding Band is cobalt. Approximate weight is 4.70 grams. This item comes in a size 12. Width is 4 MM in the widest part. Comes in a beautiful gift box. Images are for illustration purposes only. Cobalt Chromium is a newer material being used in the construction of alternative metal jewelry. It is light-weight and hypo-allergenic. Its platinum-look differentiates it from both tungsten and titanium. Cobalt is more scratch resistant than titanium, but not quite as hard as tungsten. You can clean this item using mild soap & water or a lint free polishing cloth is recommended.