Error coins: off-centre strikes, double strikes and clipped planchets
The main types of minting error, how they arise and how to tell them apart from damage
BulgarianCoins editorial team 3 min read
Mints strike millions of coins. However good the quality control, a defective coin sometimes gets into circulation. These error coins are a separate and very interesting area of collecting. Here are the main types.
Planchet errors
Clipped planchet (clip). Planchets are punched from a metal strip. If the machine punches a circle that overlaps a hole already punched, part of the planchet is missing. The coin has a concave or straight edge in one part. An important sign: opposite the missing part, the relief along the rim is weaker, because the metal was not pressed evenly.
Wrong planchet. The coin is struck on a planchet intended for another coin – smaller, thinner or of a different metal. For example, a 1 stotinka coin on a 2 stotinki planchet. Such coins are very rare.
Lamination. Part of the surface peels off because of impurities in the metal.
Striking errors
Off-centre strike. The planchet is not centred between the dies. Part of the design is missing, and one part of the coin is blank. The value rises with the displacement – 10–20% off-centre is interesting, and over 50%, with the date intact, is very valuable.
Double or multiple strike. The coin is struck a second time after it has rotated or moved. The design is visible twice, one over the other.
Broadstrike. The coin is struck without the collar that forms the edge. It is wider and thinner, with no edge.
Brockage. A coin sticks to the upper die, and the next planchet receives a mirror-image, incuse impression from it.
Die errors
Die crack. A thin raised line on the coin, caused by a crack in the die.
Cud. A large piece of the die breaks off, and a raised, shapeless blob appears on the coin next to the rim.
Filled die. Grease or dirt fills part of the die. A detail or letter is missing or weaker.
More about die differences – in Die varieties.
Mules
A mule is a coin struck with two dies that do not belong together – for example the obverse of one coin and the reverse of another. It is one of the rarest errors. See Mules and coins on the wrong planchet.
What they are worth
| Error | Indicative value |
|---|---|
| Small die crack | a little above the ordinary coin |
| Off-centre strike 10–20% | several times the ordinary coin |
| Off-centre strike over 50%, with date | tens to hundreds of euros |
| Double strike | hundreds of euros |
| Mule, wrong planchet | hundreds to thousands of euros |
The price depends on how striking the error is, on the condition and on how many such coins are known.
Error or damage
Most of the “errors” people find are actually damage done after striking – knocks, scratches, wear, chemical reactions. See Is my coin an error? and be careful: some people deliberately damage coins and sell them as “errors”.
How to start
- Search among circulation coins – most errors occur on common coins.
- Use a loupe. See The collector’s essential tools.
- Compare with the normal coin in the catalogue.
- For a valuable error, consider grading – PCGS and NGC describe errors on the label.
How a coin is struck is explained in The mint: how a coin is made.
