C

Alumina (synthetic aluminum-oxide/“India” or ceramic stones) is hard enough to abrade the softer carbon steel as well as the harder stainless-steel blades, so the same stone can be used for sharpening either metal. Arkansas stones are suited mainly to carbon steel, while silicon-carbide stones are coarser and diamond stones are specialty abrasives rather than routine sharpening media [Silva et al., 2006, PMID 16459885; Acevedo et al., 2006, PMID 17262132].