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Variety and Error Glossary

By Ian Hartshorn    |   Monday, 19 April 2010

The following content comes from the Ian Hartshorn personnal website, which not longer exist since 2010. To keep this information available to the public and for a perpetuity reason, we reproduced it here.


  • Adjustment - Reduction of metal in a flan or blank to the specified weight prior to striking, accomplished by filing down the face. Such file marks often survived the coining process and are occasionally met with in coins, especially of the eighteenth century.
  • Alignment - Alignment refers to the relative positioning of the obverse and reverse designs of a coin or medal. Historically, until the last few centuries, most coins were issued with the sides rotated 180 degrees (ie. the reverse is upside down to the obverse). This is known as "Coin Alignment" or "Coin Rotation" and continues to be observed by some coin issuing nations such as the United States of America. However, most countries in recent times now align obverse and reverse at 0 (or 360) degrees. This is known as "Medal Alignment" or "Medal Rotation". See also the entry for "upset" error coins
  • Alteration - The tampering with a feature of a coin's surface such as the date, mintmark, etc. to give it the appearance of being another date, mintmark or variety. An illegal practice
  • Altered date - refer to "Alteration" a good example is the 1930 penny.
  • Assay Piece - A sample coin included in an assay, supposedly picked at random from production. Assay is the process of determining the purity of precious metal, or the result of such a procedure.


  • Bitten edge - see Clipped planchet
  • Blakesley effect - A weakly-formed rim that occurs opposite the "clip" on incomplete planchet coins
  • Blank - An unrimmed planchet or flan. Blanks are now stamped out by machine whereas in early times they were customarily cut with special shears from a cob of metal. Also see Planchet
  • Blob - An irregular raised feature anywhere on the surface of a coin. It is either a rare form of cud where the die has chipped somewhere in the middle (an effect called spalling) or, more commonly, the result of damage to the die caused by some foreign object or hard impurity in a planchet
  • Broadstrike - A coin struck outside of the collar, resulting in the coin "spreading" beyond its normal dimensions, with no edge reeding.
  • Broadstike (uncentred) - Is defined as a "broadstrike" that shows an unequal thickness of spread around the circumference of the coin. Parts of the field design should [usually] be absent, will appear at the outset to be a simple less than 10% off-centre error.
  • Brockage - A coin with only one design, normal on one side and mirror incuse on the other. This occurs when a coin previously struck adheres to the die and strikes the next planchet to pass through the press.


  • Capped die - Is caused when a struck coin adheres to the upper hammer die. Once the coin is adhered to the die face, the reverse of the struck coin becomes the new die face. When the next planchet is fed into the collar and the strike occurs, the reverse design of the adhered struck coin impresses itself into the new planchet. This struck coin is a brockage strike. The coin adhered to the upper die is known as a die cap.
  • Clash marks - see Clashed dies
  • Clashed Die(s) - The obverse and reverse dies, which have come together in the striking process without a planchet in between. Coins produced thereafter from such a pair of dies, usually show mirror-image traces of an obverse design on the reverse, or, reverse design on the obverse.
  • Cleaned coin - While any coin subjected to a cleaning process could technically be considered cleaned, this term most commonly refers to those, which have been abrasively cleaned. This reduces the value of a coin, and in general, not the preferred collectable coin. If you are considering cleaning a coin, Don't, first seek as much advice as possible.
  • Clip - see Clipped planchet
  • Clipped coin - See clipping
  • Clipped planchet - An error coin struck from a planchet that has a piece missing, usually caused by a malfunction in the blanking press. When a coin is struck on a clipped planchet, the coin metal (metal flow) takes the path of least resistance and tends to flow into the missing area of the planchet. Various types can occur; see below for individual definitions.
    Types of clips
    1. Crescent clip - A major crescent-shaped clip that is the result of an incomplete punch that breaks off along the punch line, or a loose blank repunched off-centre on top of the strip
    2. Curved clip - A blank punched out whilst overlapping a previously punched area of the metal strip. Due to the metal strip not moving forward enough between successive punchings
    3. Multiple clips - a coin which exhibits two or more forms of clip.
    4. Nip (clip)- A small portion of the coin missing, when it is caught by the stroke of the Dies striking the next planchet, some rim bruising maybe apparent as the coin is flipped by the action. Caused when the coin is not ejected properly. (contentious, as some participants consider this does not happen)
    5. Ragged clip - rare - A blank punched from an unfinished end of strip. Maybe thinner than usual but not necessarily.
    6. Rim clip - A very small clip affecting the rim or border, these coins can have a piece missing, and the type of clip being hard to detect. Or the edge of the coin can appear complete, as the metal flow is force out to the collar die, but still showing a weakness on the rim or border at the effected area and at times points opposite the clip.
    7. Straight clip - A blank punched from the periphery of the strip, with the ends being the more common. Caused by the punching tool overlapping the ends
  • Clipping - The practice of removing slivers of precious metal from the edges of coins and passing the reduced-weight coin at original value, retaining the slivers as profit. Graining and edge inscriptions were adopted to prevent this.
  • Circulation strike - A regular issue coin, struck on regular planchets by dies given normal preparation. These are the coins that the Mint places into circulation.
  • Collar die - A restraining device used in the striking stage of coin production, which encases the planchet and allows it to be struck centred by both dies; in the case of errors, a fault in the collar will result in broadstruck and off-centre errors.
  • Counterfeit/Forgery - An imitation of a numismatic item intended to deceive and/or defraud.
  • Countermark - These are generally applied singularly, and in most cases indiscriminately on either side of the "host" coin, by another government, or to indicate revaluation.
  • Counterstamp - The coin being counterstamped is placed between new dies and struck as if it were a planchet, such as the holey dollars and dumps.
  • Cud - A lump on a coin, struck by a die from which a piece has broken off.
  • Curved based letters - see fishtailing


  • Die break - Where a piece of the die face has broken and lifted from the die, but still in place. A coin struck from such a die will exhibit a die crack like line, around the edges of the broken piece, and that part of the face of the coin effected, is usually incused, or a step down like appearance.
  • Die cap - see Capped die
  • Die chip - A fragment breaking off a die. The metal flowing into the resulting hole during striking, creating a raised lump on the surface of the coin
  • Die clash - see clashed die
  • Die crack - Is were a crack has formed on the die, due to substantial pressure or use. The metal from the planchet filling the crack when struck, leaving fine irregular raised line/s on the face of the coin.
  • Die defect - An imperfection on a coin caused by a damaged die.
  • Die progression - A sequence of coins struck from the same pair of dies and exhibiting a progressive change in the appearance of a particular die error.
  • Doubled Die - A common name for Hub-Doubling (see Hub doubling)
  • Double struck - A coin error, when a coin is struck twice by the die
  • Doubling - A common term used to describe the many types of Hub Doubling and Machine Doubling.


  • Edge bite - see clipped planchet
  • Elongated Coin - An oval medalet usually produced deliberately by a roller using a coin, token or medal as a planchet
  • Evasion - A close copy of a coin with sufficient intentional differences of design or legend to avoid being in violation of the counterfeiting laws. Also called an Imitation or Freak


  • Facsimile - An exact copy of a reproduction/original coin, possibly marked with wording or a device to indicate it is a copy.
  • Fantasy - Is a piece/object purporting to be a coin, struck with dies that were never officially authorized or using dies that were never used to strike legal tender issued coins
  • Field - The flat area on the face of a coin that is unaffected by the design
  • Filled die - A coin struck by a die that which had foreign matter, such as dirt, grease, oil, metal fragments or a combination, filling some part of the design, or sticking to the face of the die, preventing the coin metal from flowing into and filling the design or making contact with the die in these areas; shows as weak or missing design details and/or a rough irregular surface in the effected areas. (See "struck thru" for individual types)
  • Fin - A varying sized raised fin-like device, a replica of the area under Elizabeth 11's hair and back of neck, usually found above the date on pre-decimal copper coins, that may have been caused by ghosting and or to a lesser extent clashed dies or similar fault transmitted by the working die. (see Spur)
  • Fishtail/Fishtailing - A distortion of the letters of a legend caused by differential outward flow of metal during the pressing of dies and/or hubs. One specific instance of fishtailing is the curved-base lettering seen on some George V pennies and halfpennies.
  • Flake/Flaking - see Lamination flaw
  • Flan - see Planchet
  • Flipped strike or Flipover Double Strike (US) - a coin which has been struck correctly, and then has not ejected properly, is flipped over so that its reverse is struck a second time by the obverse die, and vice-versa in regards to the obverse side; they can be centred or off-centred


  • Ghosting - The impression of the Obverse showing through to the Reverse and vise versa. Caused by the use of soft planchets, over pressure on the presses and worn Dies. Can be light, medium or heavily ghosted, and appears on one side only, usually the reverse. These are not produced by clashed dies, but an occasional Die Clash mark may be observed on these types of coins


  • Hub doubling - The imperfect alignment of the hub pressings/blows during the die preparation, resulting in many different types of hub-doubled working dies. Coins struck by these dies will often exhibit a valley affect (a division or notching) on the serifs, legends and/or points of the devices. (Also read Machine doubling)


  • Imitation - see facsimile
  • Indented error - When two planchets are in the coining chamber at the same time. The two planchets may overlap each other, be of different sizes, or they maybe a blank and a coin together. See types below.
    Types of indents
    1. Indented strike - Occurs when two planchets are fed inadvertently into the coining chamber, with one planchet partly overlapping (on top of) the other. When the hammer die strikes this combination, the upper planchet will be forced into the lower planchet, creating a depression which is shaped similar to the upper planchet, and shows no design details in the indented area
    2. Indented strike of smaller planchet - A scarce type of indent occurs when a planchet intended for one denomination lands on top of a planchet from a different denomination in the coining chamber
    3. Indented second strike - Results from a planchet and a struck coin coming together in the coining chamber, the design of the first strike (coin) will be flattened and stretched out, in the indented area. The second planchet showing signs of a brockage

J - K - L

  • Lamination flaw - Where a piece of metal has peeled away from the coin's suface, caused by a foreign substance such as gas oxides or dirt which become trapped in the metal strip, or if the strip folds over during the blank rolling process.


  • Machine doubling (MD) - Where the die has bounced or twisted on impact and a second, lighter impression (not strike) could be delivered with the coin shifting slightly, and will exhibit a spreading affect (displaced sideways or appears pushed) of the serifs on the legends and/or devices. (Also see Hub doubling)
  • Metal flow - The movement of metal during the striking of a coin, in order to fill the design of the Die and create the desired result. Stretch marks/Striations on the surface of the coin, in the fields, can be attributed to incorrectly annealed planchets.
  • Metal transfer - see ghosting
  • Misstrike - Used to describe various types of errors. Usually results in coins that have only portion of the design appearing. Coins can appear as struck off center and as a result can still be flat but more often bent at one side so as to give the appearance of a high rim coin or a soup spoon shaped coin.
  • Mule (Hybrid) - A coin struck from dies not originally intended to be used together.
  • Multiple strikes - A coin struck more than once, as a result of not being properly ejected from the coining press

N - O

  • Off centre - Said of a coin only partly resting within the coining chamber at striking. Can be missing part or all of any edge reeding/device
  • Off metal strike - Any coin which has been struck on a planchet that isn't the right metal composition for that type or denomination of coin
  • Overdate - The date made by a mint engraver superimposing one or more numbers over a previously dated die
  • Overlapped planchet - see indented error
  • Overstrike - A totally full impression made with new dies over a previously struck coin. (also see "counterstamp")


  • Pattern - A pattern struck as a coin/s in order to obtain the final approval of the government or issuing authority before the general circulating coinage is struck. May be struck off metal and can be unifaced or full Obv/Rev arrangement.
  • Planchet - A rimmed blank, the size and weight of the finished coin, on which a coin design is stamped. (also see "Blank")
  • Proof - Coins struck using specially prepared dies and planchets, under controlled conditions. Struck 2 or more times under higher pressure. Designs maybe frosted, coloured or hologram. In earlier times a proof was a "specimen" prepared under carefully controlled conditions, perhaps with polished planchets.

Q - R

  • Ram strike - A planchet not sitting properly within the collar, forced into the collar at striking by the die, creating a high rim or raise lip, and at times struck off centre
  • Restrike - A coin struck from a genuine die at a date later than the original issue.
  • Rim Burr - A tapered spear of metal impressed into the surface of the coin, and they always occur at the rim
  • Rotation - see Alignment


  • Scalloped letters - see Fishtailing
  • Short planchet - see Clipped planchet
  • Slipped collar - See Ram Strike
  • Specimen - A coin with a special finish, less than proof in quality but superior to the general circulating coin
  • Split Planchet - A type of lamination error, where the split can leave a coin in two halves, one obverse and one reverse. As some do not break fully open, a significant portion of the coin can be missing or can have the two halves still attached at some point
  • Spur - A varying sized raised spur-like device, a replica of the area under King George V's chin and his vestments, usually found alongside lettering on older coins, that may have been caused by ghosting and or to a lesser extent clashed dies or similar fault transmitted by the working die. (also see "Fin")
  • Striation - See Metal flow.
  • Struck outside the collar - (term becoming redundant) see Broadstrike
  • Struck partly outside collar - A coin that only partially sits within the collar, leaving an uneven edge, and/or incomplete reeding. That part of the coin outside the collar, having no restriction to metal flow, will exhibit the traits of a broadstruck coin.
  • Struck thru ## - A general term describing any number of foreign objects between a die and planchet at the time of striking. Also see Filled die
  • Struck thru dirt - Devices and/or lettering not being fully struck up. Caused by a build up of dust in the design of a die
  • Struck thru grease - Incuse marks on the surface of a coin, generally rough and irregular, caused by oil/grease or the like, depositing onto the die, after it was wiped with an oily rag or oil weeping from the machinery
  • Struck thru lint - Small incuse mark/s on the surface of a coin caused by stray hairs, threads and the like coming between a die and planchet
  • Struck thru object - An incuse impression of a miscellaneous object, which has found its way between a die and planchet


  • Thin planchet - A planchet that is thinner than the tolerances allowed for. Caused by a fault during the rolling of metal ingots (bars) or where the ends of a metal strip have not been trimmed back far enough. These coins generally exhibit a weak or soft strike
  • Trial piece - A coin struck to test the properties of a die. It may not be a complete design, but, may be struck on different metals

U - V

  • Uniface - A coin which has been struck with a design on one side only. The other side is blank. Normally uniface coins are patterns but ocassionally are found as errors caused by a faulty striking process.
  • Unique - An item of which one example only is known to exist.
  • Unpublished Variety/Error - An example of a coin, token or medal with a difference, ie - lettering, metal content, overdate unknown date etc, which has not been listed in numismatic writings or in a journal.
  • Upset - A variation from the normal alignment of obverse and reverse dies. More prevalent on pre-decimal coins, this was caused by one or both dies rotating in the coining press. Nowadays, it only occurs as a machining error as dies have keyways cut to prevent rotation.


  • Weak strike - A coin exhibiting an incomplete strike (not fully formed) all over, or a partial incomplete strike of the design. Caused by insufficient pressure to push metal into all the nooks and crannies of the die, improper die spacing, or the planchet being thinner than normal. Often an Uncirculated coin will look like a used example. Also see thin planchet
  • Wrong planchet - Any coin struck on a planchet that wasn't intended for that denomination

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