1783 Treaty of Paris Medal. White Metal, with Copper Plug. 42.9 mm. By John Reich. Betts-610, Eimer-804, BHM-255. About Uncirculated.Forty percent of the surface still in its bright silvery finish, the rest affected -- to one minor degree or another -- by tin pest. The tiny copper plug, used as an electrolyte in this medal, has failed its job of preventing the tin pest oxidation so prevalent in medals of this composition. One of the most famous medals celebrating the Treaty of Paris, which officially recognized the end of the American Revolutionary War. Even with the light oxidation, this is an attractive example of this historic medal.