Q: What does proof condition mean in relation to U.S. gold coins?

A: The term “proof” refers to a specially-made coin distinguished by sharpness of detail and usually with a brilliant, mirror-like surface. These coins are minted with the intent they will be kept out of circulation by coin collectors.

Proof refers to a method of manufacture as opposed to an actual grade. The term also implies mint condition unless otherwise stated. A coin can be a "proof", yet be in less than mint condition. Mishandled proofs can grade below mint state. For example, you may see a "PR50" coin on the market.  This is a coin minted using the special "proof" process, but is in less than "mint state" (probably due to it's original owner needing to spend the coin at some point thereby putting it into circulation and exposing it to wear).

Some gold coins that were intended for circulation have been found to also have a deep, mirror-like finish even though they are not “proofs”.  Dealers as well as collectors call this "proof-like." The key word is “like” for they are not proof coins and will not command the same price as actual US gold proof coins.