... wedding bands,black tungsten rings,wedding ring We are Cobalt jewelry,cobalt rings tungsten, ceramic jewelry manufacturer in mainland China. ... an OEM factory. We manufacture and export various of Cobalt tungsten, ceramic Watches, rings, bracelets, which can be ... shipping when the ring is sent back.Tungsten Carbide Properties Hardest metal on earthExtremely scratch-resistant4x harder than Titanium5x ...