 This luster is caused by a metallic film that was applied to the transparent surface of a glazing, which contains silver and copper nanoparticles dispersed homogeneously in the glassy matrix of the ceramic glaze.These nanoparticles are created by the artisans by adding copper and silver salts and oxides together with vinegar, ochre, and clay on the surface of previously-glazed pottery.The technique originated in the Muslim world.