Diamond-coated sharpening devices remain permanently flat, and are especially suitable for tools with straight blades, as well as for producing flat surfaces (e.g. backs of plane and chisel blades, plane soles, scrapers). Also suitable for carbide coated cutters, tool steels, HSS and non-metal materials (glass, ceramic, etc.). We recommend moistening diamond-coated sharpening devices with water and grinding with little pressure. * Monocrystalline diamonds are significantly more wear resistant than the polycrystalline diamonds used to make lesser quality diamond sharpening tools.