Grading
What Is a Proof Coin?
Not a grade. Not a condition. A method of manufacture.
Reviewed July 2026
A proof coin is not a grade. It is not a condition either, and it is not a synonym for perfect. Proof describes how a coin was made: struck for collectors rather than for commerce, from specially prepared dies and blanks, and never intended to buy anything. Get that straight and the rest of the vocabulary falls into place.
Proof is a manufacturing category
An ordinary coin is struck once, fast, by dies that are working hard to make millions of pieces. A proof is made deliberately, with prepared surfaces, to produce a sharply defined coin with mirror-like fields. Because the coin exists to be looked at rather than spent, it is packaged and sold as a collectable from the moment it leaves the Mint.
Since 1968, proof coin production has taken place at the San Francisco Mint, having moved there from Philadelphia, and proof coins gained the S mint mark at that time. That is why so much modern proof coinage carries an S.
Proofs are graded on the same scale
Like circulated coins, proofs are graded on the Sheldon scale from 1 to 70. The only difference is the prefix: PR or PF, distinguishing them from circulation strikes. A PR-65 proof and an MS-65 business strike sit at the same rung of the same ladder; they are different kinds of coin. Proof coins graded 60 to 70 mirror the uncirculated grades exactly, with the single difference that the coin was not made for circulation. A PR-63 is sometimes called a Choice Proof.
The impaired proof
Now the interesting case. What happens when a proof coin, made to be admired, ends up in somebody's pocket? It picks up wear, and it drops below 60 on the scale.
Those coins are classified as Impaired Proofs. They are deliberately not listed alongside circulated coins, because the categories mean different things: a circulated coin did the job it was made for, while an impaired proof suffered an accident. The distinction matters to collectors because an impaired proof is a damaged collectable rather than a well-used tool. Pattern coins that accidentally escaped into circulation fall into the same category.
What proof does not mean
- It does not mean the coin is rare. Modern proof sets are struck in large numbers.
- It does not mean the coin is flawless. Proofs are graded 1 to 70 like anything else.
- It does not mean the coin is silver or gold. Proofs are struck in whatever the issue calls for.
- It does not mean the coin is old. The Mint sells new proof sets every year.
Handling a proof
Proofs are the coins most easily ruined by good intentions. Their mirrored surfaces show every fingerprint, and the oils in a fingerprint are corrosive. Album slide marks, the fine parallel lines left by pushing a plastic slide across a coin, are found mostly on proofs for exactly this reason.
The United States Mint's advice is unambiguous: modern proof sets and commemoratives should be bought and sold in their original cases and capsules, and when you insert or remove a coin you should bow the packaging by pressing opposite sides inward rather than sliding the coin against the plastic. Everything else is in how to store coins, and the reason not to polish one is in how to clean coins.
Sources: Sheldon coin grading scale for proof grading and impaired proofs; United States Mint, Mint Marks for the 1968 move to San Francisco.
Frequently asked questions
What is a proof coin?
A proof is a method of manufacture, not a grade and not a condition. Proof coins are struck for collectors rather than for circulation, using specially prepared dies and planchets, and they are graded on the same 1-to-70 scale as ordinary coins but prefixed PR or PF.
What is the difference between proof and uncirculated?
Uncirculated describes a coin struck for circulation that never circulated. Proof describes a coin that was never intended to circulate at all. An uncirculated coin can be graded MS-60 to MS-70; a proof of equivalent quality is graded PR-60 to PR-70. The distinction is about how and why the coin was made.
What is an impaired proof?
A proof coin that shows signs of circulation or mishandling and so grades below 60. Impaired proofs are classed separately rather than being listed alongside circulated coins, because they were never issued or intended for circulation in the first place.
Do proof coins have a mint mark?
Modern US proof coins usually carry an S. Proof coin production moved from the Philadelphia Mint to San Francisco in 1968, and proofs gained the S mint mark at that point.
More on grading
The Coin Register is an independent educational resource. It is not affiliated with the United States Mint, the American Numismatic Association, any grading service, any dealer, or any site previously published on this domain. Nothing here is an appraisal, a price quote, or investment advice. Coin values change constantly; check a current price guide and a reputable dealer before you buy or sell.