A proof coin
is a coin struck using a special, high-quality minting process, and made especially for collectors. Modern proof coins often have mirror-like fields
and frosted devices
, although proof coins struck prior to the mid twentieth century are often distinguished only by their high quality surfaces. In all cases, the term proof
always refers to a type of coin, or the way it was struck, and not to a coin's grade.
See Also: Reverse Proof Coins
You should never see proof coins
in circulation, because they are made for collectors, and sold by the mint for more than face value.