How to use this hub
Errors are organized here by the stage of manufacture that produced them. If you already know which family your coin belongs to, jump to it. If you do not, start with the master guide's triage method, which sorts a coin into a family before you identify the type. Each entry below gives the mechanical cause, the identifying features, the confirmation test, and the damage look-alike that most often gets mistaken for it. The die-error family has its own hub at doubled die identification; it is summarized here for completeness.
Die errors: defects in the die
Die errors repeat. The die is wrong, so every coin it strikes is wrong in the same way until the die is replaced. That is why die errors are cataloged and attributed by number, and why their populations, while sometimes large, are finite.
Doubled die
Cause: the die was hubbed twice, misaligned. Features: rounded, separated secondary image at full height; notched serifs. Test: the doubling matches a listed die's description and markers. Look-alike: machine doubling, which is flat and shelf-like. Full treatment at the doubled die hub.
Repunched mint mark and over-mint-mark
Cause: the mint mark punch was applied more than once, or a different mint's punch over a first one, in the hand-punching era. Features: rounded secondary mint mark image, separated or rotated. Test: matches a listed RPM or OMM. Look-alike: machine doubling of the mint mark; die deterioration swelling.
Die crack, die chip, cud
Cause: progressive fracture of the die in use. Features: a raised line (crack), a raised blob (chip), or a raised featureless area at the rim (cud). Test: raised, not incuse; consistent with die state. Look-alike: a scratch or gouge, which is incuse. The three compared.
Die clash
Cause: dies struck each other with no planchet between them, transferring a faint image of each to the other. Features: incuse ghost of the opposite side's design in the fields, in the correct mirror position. Test: the ghost image matches the opposite die's design exactly. Look-alike: environmental staining in the shape of a device.
Die break and retained cud
Cause: a piece of the die broke but remained in place, striking coins with the broken piece slightly displaced. Features: a section of the design offset in height or position, with a crack around it. Test: the displaced area is complete design, raised. Look-alike: a bent coin.
Planchet errors: defects in the blank
Planchet errors are unique. The defect is in one blank, so one coin carries it. They are described by type and confirmed as genuine, not attributed by number. Weight and edge examination are the primary tests for this whole family.
Clipped planchet
Cause: the blanking punch overlapped a prior hole (curved clip), the strip edge (straight clip), or a defective strip end (ragged clip); an elliptical clip comes from a distorted strip. Features: a missing section of the coin with the corresponding edge shape; weakness in the rim and design directly opposite the clip. Test: the Blakesley effect — the opposite rim is weak because the upsetting mill could not build it. Photographing it is the confirmation. Look-alike: a coin with a piece cut or filed off, which has a bright, sharp cut edge and a full opposite rim.
Lamination
Cause: an impurity or gas pocket in the alloy caused a layer to separate. Features: a thin flap of metal lifted from the surface, or a shallow irregular missing area with a layered, stepped edge. Test: the flaw follows the metal's grain and shows a clean separation plane. Look-alike: corrosion or environmental damage, which has an eaten, pitted surface rather than a clean layer. Error vs damage covers this pair in detail.
Split planchet
Cause: a severe lamination running through the whole planchet split it into two. Features: a coin that is too thin, with one face showing normal design and the other showing a rough, striated surface (split before strike), or two thin halves each with one struck face (split after strike). Test: weight is well under standard; the split face shows metal grain, not tool marks. Look-alike: a coin ground down on one side, which shows parallel abrasive marks.
Wrong planchet and wrong metal
Cause: a blank for another denomination, another country, or the wrong alloy entered the press. Features: wrong diameter, wrong weight, wrong color, design incomplete or spread if the blank was the wrong size. Test: weight and diameter match the intended planchet of another coin, not this one. Color proves nothing. Look-alike: a plated, toned, or chemically altered normal coin — same weight, same diameter, different color.
Unplated, improperly annealed, and alloy errors
Cause: a planchet skipped plating, was annealed at the wrong temperature, or was made from an improperly mixed alloy. Features: wrong surface color or texture across the whole coin, at correct weight and diameter. Test: correct weight rules out wrong planchet; surface characteristics match the known error type. Look-alike: environmental toning and chemical exposure, which are the usual explanation for an odd-colored coin.
Weight settles most planchet questions. Weigh before you decide.
Striking errors: defects in the strike
Striking errors are also unique. The planchet was fine and the dies were fine, but something went wrong when they met. Position, alignment, the collar, foreign objects, and repeat strikes are the causes.
Off-center strike
Cause: the planchet was not fully within the collar when struck. Features: part of the design missing, a blank crescent, the coin usually not round, no reeding on the unstruck portion. Test: the struck area is fully detailed and the coin's thickness is normal in the struck area. Valued by percentage and date visibility; estimating percentage is its own guide. Look-alike: a coin with a section damaged or ground away, which retains a full round outline.
Broadstrike
Cause: the collar failed to engage, so the coin spread under strike pressure with nothing to contain it. Features: full design on both sides, coin wider and thinner than normal, no reeding, rim absent or spread. Test: diameter is larger than standard, weight is correct. Look-alike: a coin flattened by a roller or press after minting, which shows the design distorted rather than complete. Off-center, broadstrike, and MAD compared.
Misaligned die
Cause: one die was off-center relative to the collar and the other die. Features: one side shows an off-center strike while the other is normal and centered. Test: the misaligned side's design is complete but shifted; the opposite side is normal. Look-alike: an off-center strike, which affects both sides.
Struck through
Cause: a foreign object — grease, cloth, wire, a metal fragment, a staple — lay between die and planchet. Features: a weak, missing, or textured area on one side matching the object's shape; the rest of the strike is normal. Test: the affected area shows the object's texture (cloth weave, wire shape) or a smooth grease-fill; no displaced metal. Look-alike: a worn or damaged area, which shows abrasion rather than an impression.
Brockage
Cause: a struck coin stuck to a die and became the die for the next planchet. Features: one side carries a mirror-image, incuse impression of the design that should be raised on the other side. Test: the incuse image is a reversed, expanded copy of the opposite die's design. Look-alike: a coin pressed against another coin in a vise after minting, which shows a crude, partial, non-expanded impression.
Capped die
Cause: a coin stuck to a die through many strikes, deforming into a cap around the die. Features: a deeply cupped coin with a thin, spread wall; the die face impressed inside. Test: the cap's geometry matches the die; the wall shows strike-thinning, not tool marks. Look-alike: a coin hammered or spun into a cup shape, which shows tool marks.
Double strike and multiple strike
Cause: the coin was struck, did not eject, and was struck again in a different position. Features: two full or partial impressions of the design, offset, rotated, or flipped; the second strike often flattens the first. Test: both impressions are fully struck design, and the geometry is consistent with a coin moving between strikes. Look-alike: a doubled die, which shows the same doubling on every coin from the die; a vise impression, which is crude.
Die adjustment strike
Cause: the press was struck at low pressure while being set up. Features: a weak, incomplete design across the whole coin, at correct weight and diameter. Test: the weakness is uniform and the coin has full weight and a normal edge. Look-alike: a heavily worn coin, which shows wear on the high points first, or a coin struck on a defective planchet.
Identifying errors from photographs
Most error coins you evaluate will be in listings, not in your hand, and a listing photograph can show or hide almost everything on this page. Learn what each error needs in a photograph and ask for it. An off-center or broadstrike needs a straight-on image of both sides and a clear view of the edge, because the edge is where the collar's absence shows. A clip needs the clipped edge and the rim directly opposite, for the Blakesley effect. A lamination needs a raking-light image of the separation plane. A wrong-planchet claim needs the weight on a visible scale and a diameter measurement, because a photograph of color proves nothing. A struck-through needs a close image of the affected area's texture. A brockage needs both sides, so you can check that the incuse image is the reverse of the raised one.
Scale and orientation help too. A photograph with a ruler or a normal coin of the same denomination beside the error lets you judge a broadstrike's spread or an off-center's percentage without trusting the seller's number. An edge photograph should show the full circumference, rotated in segments if necessary, so that reeding, seams, and clip edges are all visible.
A seller who provides only one side, only one angle, or only a flattering overhead shot is either inexperienced with errors or avoiding the test. Either way, do not buy an uncertified error without the image that would confirm it. Full edge photography shows what a complete edge record looks like, and it is the single most requested image in the error market for good reason.
Multiple errors and dramatic pieces
Errors compound. A planchet can be clipped and then struck off-center. A coin can be struck through grease and then double struck. A broadstrike can carry a die crack. Each additional error is described separately on a certification label, and dramatic multi-error pieces are among the most valuable coins in the error market because each combination is rarer than its parts. They are also among the most faked, because a crude vise job can imitate a stack of errors to an untrained eye.
Sequence matters too. The order in which the errors occurred is usually readable from the coin. A clip that was struck off-center shows the clip's weak rim inside the struck area, because the planchet was clipped first. A double strike where the second strike is off-center shows the first strike's design flattened under the second. Reading that sequence and finding it physically consistent is part of confirming that the piece is genuine, and a multi-error coin whose sequence makes no mechanical sense is a fabrication.
Evaluate a multi-error coin one error at a time. Confirm the clip by the Blakesley effect. Confirm the off-center by the edge and the complete strike of the struck portion. Confirm the second strike by its full detail and consistent geometry. If every component passes its own test, the combination is plausible; if any component fails, the whole coin is suspect. And for anything of value, certification is the only evidence the market accepts, because the services examine exactly this way and describe exactly what they confirm.
The look-alike family
Every entry above ends with a look-alike, and they fall into a small number of categories that the not-an-error hub covers in full. Incuse marks are tools. Bright, sharp edges on a worn coin are recent damage. Color changes at correct weight are chemistry. Flat shelf doubling is machine doubling. Mushy rim doubling is die wear. A missing mint mark is usually a Philadelphia coin. If your coin's feature fits one of those descriptions, it fits the look-alike, and no amount of hoping changes that.
Confirmation and certification
Planchet and striking errors are confirmed by the physical tests above and then certified as genuine by a grading service, which describes the type on the label. Because these errors are unique, the certification is the market's evidence that the coin is real, and for anything of meaningful value it is close to mandatory. Error coin grading and certification covers which services handle errors, what to expect, and how to submit.
Value is set by drama, rarity for the denomination, and grade, and it is found the same way every time: search the error type and denomination, filter to sold, and look at certified examples. The raw error return checklist is worth reading before you buy an uncertified example of anything on this page.
Certified examples are the best reference for every type on this page. Search the type name and study what the graders confirmed.
Frequently asked questions
What are the three types of mint errors?
Die errors, planchet errors, and striking errors, named for the stage of manufacture that produced them. Die errors repeat across coins; planchet and striking errors are unique to each coin.
What is the most common mint error?
Minor die cracks and chips are the most common die errors. Small clips and minor off-center strikes are the most common planchet and striking errors. All are usually inexpensive.
How do I confirm a clipped planchet?
Look for the Blakesley effect: weakness in the rim and design directly opposite the clip. A cut or filed coin has a full opposite rim and a bright cut edge.
What is the difference between a broadstrike and an off-center strike?
A broadstrike has the full design but spread wider because the collar was absent. An off-center strike is missing part of the design because the planchet was not fully under the dies.
Can a coin have more than one error?
Yes. Multiple errors on one coin are common in dramatic pieces — an off-center double strike, a clipped planchet struck off-center — and each error is described on the certification label.