Error coins and varieties
What each error type looks like, which ones carry real premiums, and the known varieties by year with the test that confirms them.
The error types that matter
| Error | What it looks like |
|---|---|
| Doubled die | The design was impressed twice on the die at slightly different angles, so every coin from it shows doubled letters or digits. Different from machine doubling, which is flat, shelf-like and worthless. |
| Repunched mint mark (RPM) | The mint mark was punched into the die more than once; a second outline shows beside or below the main letter. Common on 1940s–1960s cents and nickels, usually worth a few dollars to a few hundred. |
| Off-centre strike | The blank was not centred under the dies; part of the design is missing and a blank crescent shows. Value rises with the percentage off-centre as long as the date is visible. |
| Wrong planchet | A coin struck on a blank meant for another coin or another year: the 1943 copper cent, the 1944 steel cent, a cent on a dime planchet. The valuable ones are the ones that need a scale. |
| Clipped planchet | A curved or straight bite out of the edge where the blanking press overlapped a previous cut. Small premiums; large or multiple clips more. |
| Die cracks, cuds and breaks | Raised lines or blobs where the die cracked. A cud (a piece of the die missing at the rim) is worth more than a hairline crack. |
| Lamination and struck-through | Peeling metal from a flawed alloy, or a coin struck through grease, cloth or a stray fragment that left an impression. |
Rule of thumb: an error made by the Mint before the coin was struck or during the strike can be valuable; damage done afterwards (scratches, hammer marks, acid, a vise) is worth nothing, however strange it looks.
Frequently asked questions
How do I know if my coin is an error coin?
Compare it with a normal example of the same date: look for doubled letters, a second mint mark, missing design, a bite out of the edge or the wrong colour and weight. Then check the year's value page for the varieties known for that date and the tests that confirm them.
Are error coins worth money?
Some are. Major doubled dies, wrong-planchet strikes and dramatic off-centre coins sell for hundreds to hundreds of thousands of dollars; minor die cracks and small clips add a few dollars. Damage after the coin left the Mint adds nothing.
What is the difference between a doubled die and machine doubling?
A true doubled die shows rounded, separated duplicates of the letters, the same on every coin struck from that die. Machine doubling is a flat shelf beside the letters caused by a loose die bouncing at the moment of striking, and it carries no premium.
Where do I sell an error coin?
Minor errors sell on eBay or to a local dealer. Anything worth more than a few hundred dollars should go to PCGS or NGC first; an authenticated, graded error sells for more and sells faster, through dealers or auction houses that specialise in errors.