Our rings Are Hypoallergenic. If you are looking for a ring that is scratch resistant and forever keeps its shine, then our Tungsten Carbide rings are for you. 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 nor turn your fingers green.