Tungsten Carbide is ranked second hardest next to diamond on the Mohs scale, diamond being a 10 followed by Tungsten Carbide as 9. All of our Tungsten rings are Cobalt Free and hypoallergenic. Our rings will not cause skin irritations or turn your fingers green. Due to the Hardness of Tungsten, these rings can be laser engraved, but not hand engraved. All ring come with a 30 days 100% Money Back Guarantee and a FREE ring Box.