Niello. A design entirely of engraved lines. Niello medals have a flat background or field which is engraved (cisele). They can be struck from dies which have very fine lines or niello medals can be hand engraved (one at a time). Niello dies must be handled with extreme care, since they are entirely of fine raised lines they are susceptible to damage.

Early niello objects, including medals, had the incised lines filled with a material composed of copper, lead and sulphur of borax – a form of black fill-in which was fired and polished. Such objects lacked modulated relief as all niello is biplanar – of two planes – incised lines in a flat surface with a fill-in of the incised lines.

The modern photoengraving process can produce medals of this type (photoetched) from a black-and-white drawing – and the Paris Mint has issued numerous medals in this cartoon-like style – however the process is not widely used elsewhere in modern times. True niello has the black fill-in of the sulphur/borax composition. An imitation niello would be made in modern times with black enamel or crayon fill-in. A bas-relief model is not required for a niello medal, only a drawing.