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.
Many new coin dies started out life in the coining presses by having a matte finish on the body or head of the coin, then as the coins were stamped out, the frosted matte look began to disappear because of die wear. Rather than resandblasting to create the frosty look, the mint just took a time short cut and repolished the whole die. Depending on the size of the coin and the stamping pressure required, in some cases the proof or proof like coin can lose the frosty look by the time 45 to 100 coins have been through the die. This is basically why only a few cameo proof like frosted coins are seen in business strikes or in many proof coins. It also sets up a rarity factor for the frosty proofs or proof likes before 1968 including Special Mint Set Coins, Kennedy Half Dollars, Franklin Halves, Washington Quarters, Roosevelt Dimes, Jefferson Nickels, and Roosevelt Dimes.