How do you know the difference between proof coins versus regular issue coins?

Answer by  nuttree (1596)

Proof coins are produced with new dies, before the regular issue coins are produced. They are struck to test the quality of the dies, and also for archival and collection purposes. Special measures are taken to improve the quality of proof coins; the dies are polished and sometimes chemically-treated.

Answer by  BrianSJ (524)

Proof coins are never intended to be circulated and are minted within sets that are not intended to be broken apart. They are usually struck with higher relief in the features. Depending on the coins, they may have mirror-like finishes and matte finishes that are not reflective. In either case, a coin's details are more clearly visible in proof coins.

Answer by  Darkephoenix (1789)

Proofs are higher grade coins and will usually be packaged and labeled as such. This helps hold the value of the coin.