Most pre-1968 proof coins were produced by the Philadelphia Mint and consequently do not have a mint mark. A proof coin is the method of manufacturing that is used and not a grade. Some countries strike proof coins from both polished sheets and polished dies according to their press releases. The U.S. Mint has followed this practice for a number of years. In most cases it's very easy to tell the difference in proof coins and everyday use business strikes.
Proof coins have brilliant mirror finishes and in most cases full detail is shown.
Matte Proof Coins Matte proof finish is where the whole striking surface of the coin stamping die was sandblasted and they have a granular look over the whole coin. In the early Matte Proofs, if the coin went into circulation, it is almost impossible to tell if it was a proof. In the U.S., matte proof pennies, nickels, and many gold proofs were made between the years of 1908 and 1916. Some 1921 and 1922 matte proof silver dollars were also struck. Brilliant proofs are where the whole die has been polished.