U.S. Proof Sets start out as coinage blanks that are polished and cleaned to assure high quality in striking. They are then hand fed into the coinage press one at a time. Each blank receives two or more strikes from the dies which are cleaned or polished after every 15 to 25 impressions.
The dies are frequently replaced to avoid any imperfections. The entire coinage operation is done at a very slow speed with extra pressure. Using gloves or tongs, the finished proofs receive several inspections before they become sonically sealed in special packages by the U.S. Mint.
The striking of proof coins was temporarily suspended from 1943 to 1949, and again from 1965 to 1967. During this latter period “Special Mint Sets” were struck. Production of Proof Sets resumed again in 1968 and were minted only at the San Francisco Mint. In 1970, U.S. Proof Sets had ceased being made in silver, but in 1992 production in silver had once again started. Proof Sets have traditionally increased in value making them a true asset to own in ones collection.
Composition from 1939-1964: 90% Silver, 10% Copper Composition Jefferson Nickel: 75% Copper, 25% Nickel Composition Jefferson Wartime Nickel: 56% Copper, 35% Silver, 9% Manganese Composition Lincoln Cent: 95% Copper, 5% Tin and Zinc Composition from 1965-1998: 75% Copper, 25% Nickel (Net of 40% Silver)
U.S. Proof Coin Sets are sold with the original U.S. Government protective plastic packaging.