In the process's of plating the zinc it is not use the C101 Oxygen Free Copper which it is compact. The plating in the fabrication of the coins will result in an porous cooper layout. The zinc core, oxide very fast given an white-grey oxide which I see on the Cujon coins and has a normal Cu surface color. The OP coin color it is more versus a toning color and could be obtain relative easy on this color form.