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Error Coins: Types and Verification

Off-center strikes, double dies, mules, broadstrikes. The taxonomy of error coins and which categories the market actually rewards.

The setup: Mint errors range from minor production variation to recognized, attributable error types. Authentication, the error mechanism, denomination, date, condition, and current demand all matter.

Error Categories That Pay

Doubled Dies (DDO/DDR)

A doubled-die variety originates during die creation. The 1955 DDO Lincoln Cent is a prominent example. Verify the attribution with specialist references and current records.

Mules

A mule combines dies not intended to be paired. The Sacagawea dollar and Washington quarter mule is a prominent example; verify the attribution, known examples, and current auction records directly.

Off-center strikes

The planchet was not centered during striking. The amount off center, whether identifying details remain, denomination, composition, condition, and authentication all affect collector interest.

Wrong Planchet

A coin struck on a planchet intended for a different denomination. Confirm weight, composition, dimensions, attribution, and certification before drawing a market conclusion.

Repunched Mint Marks (RPM)

A repunched mintmark is an attribution question, not a universal premium. Use a specialist reference and compare the exact certified variety with current records.

Errors That Don't Pay

  • Post-mint damage: Hammer marks, tooling, drilled holes. Worth less than face.
  • Greaser strikes: Filled die from grease. Common, low premium.
  • Minor misalignment: verify whether specialists classify it as a collectible error before assigning market significance.
  • Modern Sacagawea mule fakes: Many on eBay are altered Sacs. Authentication critical.

Find Listed Errors

Filter by error type. Many graded errors fly under the price guides.

Browse Coins →

Storage & handling

Errors are found under magnification, a USB microscope or 10x loupe is the difference between spotting a doubled die and scrolling right past it. Store the keepers in Air-Tite capsules or Saflips. See our collector gear guide →

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