Striking errors: off-center and broadstrike
An off-center strike happens when the blank is not seated properly in the press, leaving part of the coin blank and the design shifted. Value rises with the percentage off-center, and examples showing a full date are worth the most — a dramatic 40–60% off-center coin with a visible date commands a solid premium.
A broadstrike occurs when the retaining collar fails, letting the coin spread wider and thinner than normal with no reeded edge. Broadstrikes are common enough to be affordable entry-level errors, typically selling for modest premiums on modern coins.
Planchet errors: clips and wrong planchets
A clipped planchet shows a curved, straight, or ragged missing bite where the blanking press overlapped a previously punched hole or the strip’s edge. Genuine clips usually show the Blakesley effect — weakness in the rim directly opposite the clip — which helps separate them from post-mint damage.
Wrong planchet errors are the blockbusters: a design struck on a blank intended for another denomination or country, such as a cent struck on a dime planchet, or the famous 1943 copper cents struck on leftover bronze blanks. These regularly bring four to six figures depending on the pairing.
Die errors: cracks, cuds, and mules
Dies crack under the enormous pressure of repeated striking, and a cracked die leaves raised lines of metal on every coin it strikes. When a piece of the die actually breaks away at the rim, the coin shows a raised blob called a cud — a popular and collectible die stage.
A mule pairs two dies never meant to meet, like the famous 2000 Sacagawea dollar struck with a Washington quarter obverse. True mules are exceptionally rare and sell for tens of thousands of dollars or more.
- Die cracks: raised, jagged lines across the design
- Cuds: raised blank blobs attached to the rim where the die broke
- Die clashes: ghost impressions of the opposite side, from dies striking each other
- Filled dies: weak or missing letters where grease packed the die (common, small premiums)
- Mules: mismatched obverse/reverse designs — rare and valuable
Identify odd-looking coins with CoinVault Pro
Found a coin that looks wrong? Scan it with CoinVault Pro — the AI recognition identifies the type and date, and comparing your coin against how the design should look is the first step in separating a genuine mint error from post-mint damage.
Log candidates in your collection with photos and notes, check live sold prices for similar errors, and share your best finds with the app’s community feed, where other collectors can weigh in.