The U.S. Mint started producing proof coins in the 1850's. Very few proof coins were minted prior to 1856. Some of these are presentation pieces or also called pattern coins made for the demonstration of new designs prior to regular production issues.
The term proof coin is not related to the coin's condition, but rather to its method of minting. Normal production coins, even in mint state condition, have coruscating, frosty luster, soft details, and minor imperfections. Proof coins are easily distinguished by their sharp detail, high wire edge, and extremely brilliant, mirror like surface. All proof coins were originally sold by the mint at a premium price.
