ErrorCoins.co
Mint error identification laboratory

Follow the metal.
Not the hype.

Learn whether an unusual coin was made that way at the mint, repeated from a specific die, or changed after it entered circulation.

Start error-or-damage triageOpen identification workflow
A cent standing on its edge beside an out-of-focus jeweler's loupe
Production firstPlanchet · die · strike · collar · edge
Damage controlsHeat · impact · corrosion · tooling · plating
Evidence over asking priceSold comparables · certification · exact match
Focused marketplace pathsError-coin category searches · sold evidence
Start here

Three different questions

Most bad attributions happen because a collector jumps directly from “this looks strange” to a valuable error name.

A coin struck off center leaving a crescent of blank unstruck metal
①

Mint error?

A one-off event involving the blank, planchet, strike, collar, edge lettering, or ejection.

Browse error types →
A row of identical cents showing the same surface character on every piece
②

Die variety?

A repeatable feature present on every coin struck from the same prepared or damaged die.

Browse varieties →
A warped and corroded coin with deep gouges across the field
③

Post-mint damage?

Impact, heat, corrosion, machinery, chemicals, alteration, jewelry use, or ordinary wear.

Compare lookalikes →

Category imagery is illustrative. Specimen photographs and diagnostic comparisons appear in the individual guides.

Diagnostic workflow

Do not name it until the evidence agrees.

  1. Identify the normal coin. Date, mint, subtype, composition, weight and edge standard.
  2. Describe the anomaly. Raised or incuse? Missing metal or displaced metal? Local or global?
  3. Photograph everything. Both faces, complete edge, angled light and scale.
  4. Test a minting mechanism. The explanation must account for every visible feature.
  5. Try to disprove it. Compare damage, alteration, plating and ordinary die state.
Run the triage toolCheck weight evidence
Split macro comparing crisp minted relief against torn and gouged metal under identical light
Popular research paths

Start with the mechanism.

A plain copper disc with a square-cut edge and no raised rim

Blank Planchet Type 1

An unstruck blank punched from coinage strip before the upsetting mill forms a raised rim.

A plain copper disc with a smooth raised rim around the full circumference

Blank Planchet Type 2

An unstruck planchet that has passed through the upsetting mill and shows a prepared rim.

A cent with a smooth curved crescent missing from one edge and the rim fading toward it

Clipped Planchet

A blanking error in which part of the coin blank is missing because punches overlapped the edge or a prior hole.

A five-cent design on an undersized round planchet beside a correctly sized coin

Wrong Planchet Error

A coin struck on a planchet intended for another denomination or another coinage specification.

Two coins of the same design side by side, one copper and one white metal

Wrong Metal or Off-Metal Strike

A design struck on metal or stock not intended for that issue.

A thin weakly struck coin beside a piece showing a rough granular interior surface

Split Planchet Before Strike

A defective planchet separates before striking, leaving a thin coin with weak or incomplete design.

Extreme macro of a raised letter with a second overlapping impression at equal height and notched corners

Doubled Die Obverse

A hubbing variety created on the die before coins are struck, producing repeated design elements on every coin from that die.

Extreme macro of a raised leaf with a second overlapping outline separating into a notch at the tip

Doubled Die Reverse

A reverse die variety with duplicated design elements created during die manufacture.

Extreme macro of a raised mintmark letter with a partial second impression beneath it

Repunched Mintmark

A mintmark was punched into a working die more than once in differing positions on older issues.

Extreme macro of a raised device with a low flat shelf of smeared metal stepping down beside it

Machine Doubling

Flat shelf-like displacement created during the strike, not a doubled die variety.

A coin with a thick smooth rolled rim and reduced diameter beside a normal cent

Dryer Coins

Coins trapped in commercial dryers can become smaller, thicker-rimmed, smooth, and rounded.

A coin with an uneven hammered rim covered in overlapping tool facets and a dished face

Spooned Coins

Repeated edge hammering produces a thick rounded rim and reduced diameter.

Marketplace reality: a seller can type “rare mint error” into a title without proving anything. Use eBay to find comparison material, not to outsource identification to the loudest listing.
Coins in clear rectangular holders with blank label strips
Collector marketplace

Compare certified examples and clearly photographed raw coins.

Search results contain seller descriptions, not independent conclusions. Compare the exact denomination, date, mint, error class, percentage or position, weight, grade, certification, and sold evidence.

Compare focused eBay listings

Affiliate disclosure: ErrorCoins.co may earn a commission from qualifying purchases.