This ring is Hypoallergenic and Comfort fit. Tungsten Carbide is a highly scratch resistant material that will stay polished forever. Tungsten Carbide is ranked second hardest next to diamond on the Mohs scale, diamond being a 10 followed by Tungsten Carbide as 9.Please note that, because of the nature of the material, tungsten rings can only be engraved by laser. All of our Tungsten rings are Cobalt Free and will not turn green or irritate the skin. If you are not completely satisfied with your purchase, you have 30 days to return the ring for a refund.