How To Tell If A Coin Is Proof?

Sel_691 has brought up an interesting fact about older proof coins. The word "proof" as applied to modern coins struck for collectors is technically incorrect. The original and correct use of the word is to describe those coins that were used to "prove" a die! It can be considered as related to the hobbing method of die-duplication. Thus the coin itself is the "proof" that the master die is good. A very few "proof" examples would be made and distributed among those who would examine them closely for any potential problem. If approved the die would be put into production... or... if it is a master, a matrix would be struck from it in steel, and the matrix used to duplicate the master die. The cloned second generation dies would be very very close to exact copies... but there are always some small difference, particularly in textural elements such as hair etc. So the "proof" coins made from the actual master would be the best of the best.... struck from the die closest to the original art, and they would be the very first coins struck, while the die was still new and unworn.

So it's easy to see that among early coin collectors there would be a very keen competition for who got to keep the "proof" strikes from a new die! And that demand would filter eventually to a decision-maker who would determine that the mint boys should make more than just two or three "proofs" so that political cronies could have them. And finally we reach the current completely "degenerate" situation in which an entire mint (SF) basically does nothing but create fake "proof" coins for the collector market. Yes I used the word fake... because the coins everyone refers to as proofs are NOT in fact proofs at all but simply collector quality production strikes. The ordinary numismatic use of the word proof is a misnomer, such that it becomes difficult (as noted by Sel_691 above) to distinguish ACTUAL proof coins, coins struck specifically to prove a die.

tmaring: I couldn't have said it better myself.
biokemist6: I think your point is equally valid, and I agree with that as well.