 Many modern reproductions do not have natural hamon because they are thoroughly hardened monosteel; the appearance of a hamon is reproduced via various processes such as acid etching, sandblasting, or more crude ones such as wire brushing.Some modern reproductions with natural hamons are also subjected to acid etching to enhance their hamons' prominence.A true hamon can be easily discerned by the presence of a "nioi," which is a bright, speckled line a few millimeters wide, following the length of the hamon.