Errors
Rare Coin Errors: What to Look For
A failure during manufacture, not damage afterward. Planchet, die and strike errors, and how to tell them apart.
Reviewed August 2026
Most odd-looking coins found in pocket change or an inherited jar left the mint in normal condition and were altered afterward: scratched by machinery, corroded, or dented in a vending counter. A true mint error is different. It is a failure that happened during manufacture, before the coin ever reached circulation, and the failure is recorded permanently in the coin's metal.
Error, variety, or damage?
These three get confused constantly, and they are not the same thing. A mint error comes from a mechanical or human failure during striking: a coin fed onto the wrong planchet, a cracked die, a blank that jams in the press. A variety is a design difference built into the dies themselves, such as a doubled die or a repunched mint mark, and every coin struck from that die pair carries it. A variety is not a mint error, even though collectors sometimes lump the two together.
Post-mint damage is neither. Scratches, corrosion, bent edges, rim dings from a coin-counting machine, and coins run over by a lawnmower all happen after the coin leaves the mint, however dramatic the result looks. Most coins presented as errors turn out to be this. A separate mint-stage artifact, sometimes confused with both, is machine (mechanical) doubling: a shelf-like flatness on part of the design caused by die bounce at the moment of striking. It is not post-mint damage, but it is also not a doubled-die variety, which comes from a mismatched hub impression baked into the die before any coin was struck. For a related but different problem, coins deliberately altered to imitate a scarcer date or mint mark, see spotting counterfeit and altered coins.
Planchet errors
A planchet is the blank metal disc before it is struck into a coin. Planchet errors happen before the strike, when the blank itself is already wrong.
A clipped planchet is missing a curved or straight bite, usually because the blank was punched too close to the edge of the metal strip, or overlapped a hole already punched. A wrong planchet error occurs when a die for one denomination strikes a blank meant for another, such as a dime design struck on a cent planchet, producing a coin of the wrong size, weight, or color for its design. A blank planchet is a disc that skipped the coining press entirely and left the mint with no design at all.
Die errors
The dies are the hardened steel tools that strike the design into the planchet, and they wear out or fail. A cud, or die break, appears when a piece of the die's face breaks away; the coin shows a raised, blank blob of metal where the missing die design should be, because metal flowed into the gap instead of being struck with a pattern. Smaller cracks in a die leave thinner raised lines across the coin rather than a full blob.
Strike errors
Strike errors happen at the moment of impact, when the planchet, the dies, or the collar that normally rings the blank are misaligned or missing.
An off-center strike happens when the planchet is not centered between the dies, so part of the design is cut off and a blank crescent of blank metal remains. A broadstrike happens when the collar that normally restrains the blank's edge is missing, so the coin spreads wider and thinner than normal; the full design is present but pushed out beyond the coin's normal diameter, and a partially seated collar can leave a ridged, railroad-track rim. A multiple strike happens when a struck coin fails to eject and is struck again, sometimes rotated or off-center on the second hit, leaving overlapping images. Brockage is a reversed, incuse impression of one side of the coin, caused when a previously struck coin sticks to a die and acts as a second, mirror-image die for the coin struck after it. A strike-through happens when grease, cloth, wire, or another foreign object sits between the die and the planchet during the strike, leaving a void or an unintended texture where the object was.
| Error | Category | What causes it | What it looks like |
|---|---|---|---|
| Clipped planchet | Planchet | Blank punched too close to the strip's edge | Curved or straight bite missing from the coin |
| Wrong planchet | Planchet | Blank meant for a different denomination fed into the press | Wrong size, weight, or color for the design struck |
| Cud (die break) | Die | A piece of the die's face breaks away | Raised, blank blob where design should be |
| Off-center strike | Strike | Planchet not centered between the dies | Part of the design missing, blank crescent remains |
| Broadstrike | Strike | Restraining collar missing at the strike | Full design, spread beyond normal diameter |
| Multiple strike | Strike | Struck coin fails to eject and is struck again | Overlapping or rotated doubled images |
| Brockage | Strike | A previously struck coin sticks to a die | Reversed, incuse mirror image on one side |
| Strike-through | Strike | Foreign material between die and planchet | Void or unusual texture in the design |
How to inspect a suspected error
- Do not clean the coin. Cleaning can destroy the surface evidence, such as flan flow lines, that confirms an error is genuine.
- Photograph both faces and the edge in good light before you do anything else.
- Compare the coin's weight and diameter to its published specifications; a wrong-planchet or clipped coin will usually miss one or both.
- Inspect the coin under magnification for tool marks, which point to a deliberately altered coin rather than a mint error.
- Separate raised features from incuse (recessed) features; a cud is raised, while a brockage impression is incuse, and confusing the two leads to a wrong attribution.
- Before making a material buying or selling decision, seek authentication from a major grading service that attributes error coins.
What decides value
An error's value comes from the same forces behind any coin's value: rarity, condition, demand, and authentication. A dramatic-looking error on a coin struck by the million, in worn condition, with no third-party attribution, is usually worth little. Rarity and condition are covered in more depth in what makes a coin valuable, and grade is defined in the coin grading scale explained. This guide does not publish price figures for specific errors, because condition, market demand, and authentication shift outcomes too much for a fixed number to mean anything.
Before you buy or sell
Do not clean the coin, and do not assume a strange feature is valuable just because it is unusual. Photograph it, measure it against published specs, and get it authenticated by a major grading service before money changes hands. See how to clean coins for why cleaning is the one step you cannot undo.
Sources and further reading
- NGC, "Variety versus Mint Error"
- NGC, "Learn Grading: What Is a Mint Error? — Part 3"
- NGC, "Mint Error Coin Chronicles: Broadstrikes"
- NGC error coin gallery
- NGC, "Double Dies vs. Machine Doubling"
For general references and grading services, see resources.
Frequently asked questions
What is the difference between a mint error and a variety?
A mint error is a mechanical or human failure during manufacture, such as a coin struck on the wrong planchet or off-center. A variety is a design difference built into the dies themselves, such as a doubled die or a repunched mint mark, and it was produced the same way on every coin struck from that die pair. See our guide to spotting counterfeit and altered coins for how altered coins differ from either.
How can I tell if damage happened at the mint or afterward?
Mint errors leave evidence consistent with what happens inside a coining press: a missing or off-center design, a shifted or absent rim, overlapping images from more than one strike, or a blank area with no design at all. Scratches, corrosion, bent edges, or a dent from a vending machine happened after the coin left the mint and are not errors, however unusual the coin looks.
Does an error automatically make a coin valuable?
No. Rarity, the coin's condition, and collector demand for that particular type of error all affect value, and a common, minor error on a common coin is usually worth little more than face value. Our guide to what makes a coin valuable covers the same four factors that apply to any coin, error or not.
How do I get a suspected error coin authenticated?
Photograph both faces and the edge, then send the coin to a major third-party grading service that attributes error types, such as NGC. Authentication matters more for errors than for most other coins, because post-mint damage and deliberate alterations are frequently mistaken for, or passed off as, genuine mint errors.
Is it safe to clean an error coin to see it better?
No. Cleaning strips original surfaces and can destroy the subtle evidence, such as flan flow lines or the texture inside a brockage, that an attributor relies on to confirm the error is genuine. See how to clean coins for why collectors leave coins alone entirely.