A newly minted proof coin is also Un-circulated coin, but the way it is manufactured that causes a difference in appearance and qualifies it as a “proof”. Coins are produced when two dies strike a blank piece of metal with tremendous force. One die is engraved with the front design for the coin, while the other die has the reverse coin design on it.
Dies used for proof sets are specially polished and treated, so coins have the best possible quality. To increase the imprinted detail, proof coins are struck twice, or more. This fine detail does not usually appear on most non-proof coins, even if they have no wear or have never been used.
Why are Proofs Set usually more expensive?
The extra effort, time, labor and production costs in making a proof coin than the respective government mints, Proof Set often have a higher price. Production of proof coins is limited. For most United States gold and silver coins, the proofs have the same amount of precious metal in them as non-proof uncirculated coins.
An uncirculated coin may show tarnish, toning, spotting, or discoloration and still remain in uncirculated condition. We recommend never clean a tarnished coin, because most cleaning will cause wear on a coin, and thus lower its grade and value.