1981 Copper Enamel Lincoln Penny Earrings in dark purple. These lincoln pennies have a dark transparent purple enameling glass that has been sifted in layers and torch fired until the glass has melted and has a glossy finish. Prior to 1982 every penny the U.S. Treasury minted was 95% copper. Today pennies are mostly zinc with minimal copper. The high copper component is what allows this process to be possible. The high zinc component turns the coin into a melted unusable pile.