Error Coins, an Introduction

By on 16th December 2017

Error coins are a fascinating and still fairly non mainstream side-line to regular coin collecting. Despite the headline grabbing stories about rare and error coins you can find in your change that are worth ‘a fortune’ that the tabloid/clickbait press try to push out (and in 99% of cases get completely wrong), most error coins are usually fairly low value and many minor errors can be picked up for just a few pounds. Error coins, just like normal coins, or anything for that matter, are only worth what people are willing to pay for them and that worth is strongly influenced by a number of factors including demand, rarity and the attractiveness of the error coin. An extra factor that plays a big role with error coins is their severity or unusualness.

Error coins have never really been a big deal in the UK until quite recently where interest in them has grown. An increase in people collecting coins has lead to more people looking closer at coins and noticing errors. People are able to instantly share images of unusual coins on social media, which in turn prompts others to look for similar unusual coins and more suspected error coins are being discovered, shown and discussed. Some error coins end up being exposed in the press (and some aren’t errors at all!), usually as a result of people asking silly inflated prices for coins on eBay, that are completely utopian and where ‘sales’ at such prices are unverifiable and are very often not genuine or completed sales.

The recent increase in interest and higher demand for error coins has also prompted many unscrupulous people to create home made error coins that have clearly been manipulated and were not originally made like that – this is essentially post-mint damage and is something which has been especially rife with the new 12-sided £1 coin. Unfortunately, due in part to the demand fuelled by the tabloid stories and people not really understanding what they are buying, many have paid too much money for ruined coins that technically no longer even have a valid face value. To be able to spot shed-made ‘errors’ it’s important to understand how coins are made, especially the bi-metallic £2 and £1 coins (some more on that further down).

Here are some error types that I have observed on UK coins over the years (note that there are other types of error coins and this list is not meant to be comprehensive). I’ll try to add pictures where possible. For those that don’t have images, and if you have such a coin and can provide good quality images, please let me know.

Minor UK coin errors (and non errors) include:

The cud at the bottom of this 2008 20p very much resembles and upside down ‘1’.

1. Die chips …

Very common on modern (post approx. 2000) UK coins. Die chips are raised blob-like lumps on the surface of the coin, usually on a raised part of the design as opposed to on the lower flat areas. They are very common on and around the Queen and depending on location, have often been termed ‘Queen with an Adam’s apple, ‘Queen with a mole’ etc. Die chips on earlier coins are practically unheard of, which seems to indicate to me that the Royal Mint procedure for striking coins has changed over the years and perhaps they are saving money by using dies beyond their normal accepted lifetime or by not properly ensuring that coins are of high enough quality before they end up in circulation (some have also speculated that the ‘business strike’ circulation coin quality is kept fairly low to encourage people who want perfect coins to purchase coins in packaged BU or proof form). Larger die breaks that also involve the rim are known as cuds. Die chips can be more interesting if they resemble something that looks intentional; see also die cracks, below.

2. Die cracks …

The same principle as with a cud, i.e. the die that was used to strike the coin is damaged through excessive use, but rather than a blob, a cracked die results in a thin raised line on the surface of a coin, which can turn into a larger blob if the faulty die isn’t changed and is permitted to strike more coins (and break further). The lines often pass through raised design elements like lettering and can sometimes run right to the edge of the coin. Cracked dies have resulted in a recent obvious-to-spot coin anomaly where the crack happen to look like an extra feature on the so-called ‘cat on mast’ 2015 Royal Navy commemorative £2.

I originally thought the 2016 Peter Rabbit 50p with ‘extra whisker’ was a die crack from seeing pictures of them. This extra whisker is also caused by damage to the die, but most likely damage from being scratched by part of the machinery called a feeder finger.

3. Unstruck blanks/planchets/flans ….

An unstruck large type (pre 1997) 50p blank, probably from the late 1960s.

Blanks, or more accurately in most cases, ‘planchets’ (or ‘flans’) are pieces of shaped metal that haven’t been struck between dies at all. In the case of coins with edge lettering (e.g. in the UK the £2 coins and the old round £1 coins) the coins-to-be have the edge lettering imparted onto them during a separate process, and it is more common where blank £2 or old £1 coins are encountered, to find them with clear edge lettering but omitting the rim milling (the ridges around the edge), which is imparted by something known as a collar at the same time as the design details are struck onto it with the two dies. Most encountered blank planchets also have a raised rim, as this is imparted onto the disc before it gets struck between the dies. Blank coins that are just shapes of metal (with or without a rim) aren’t all that attractive and while scarce, they don’t tend to sell for large amounts. Blank coins with edge lettering that was only used for one particular coin design during one year only, and are therefore accurately identifiable, are a little more desirable than a coin without edge wording or one with a motto that was used on a number of different coins or over a wide range of different dates.

Note that fake blank coins can potentially be man-made by smoothing down both sides of a normal coin. These are usually obvious to spot, as the surfaces often show tooling marks and/or are excessively polished, not to mention the thin layer of removed metal means that the ‘blank’ will weigh significantly less than a normal coin of the same type.

Note also, that 20p coin blanks are completely round. They are shaped entirely by the collar during the striking process.

4. Clipped flans …

A 1969 10p struck on a clipped flan.

Round coin-shaped blanks are cut out of sheets of metal. This is done at high speed and sometimes something goes wrong and blank pieces of metal are produced that have been clipped on the edge (at least once) by the sharp press that cuts out the metal discs. When these irregular shaped blanks are struck into coins and released into circulation they are known as a ‘clipped planchet’ or ‘clipped flan’ error. The clip itself can range in size from being just a tiny, almost unnoticeable irregularity on the rim to being a fairly large crescent shaped chunk out of the coin. It is also possible (and much rarer) for a coin to have more than one clip in different positions.

5. Partial collar error …

When the planchet (blank piece of metal) is struck with the dies to impart the design on both sides, it is at the same time surrounded by a collar  which ensures the resulting coin is perfectly shaped, either round or with ‘sides’ in the case of the new £1, the 50p and the 20p. For coins with edge milling the collar also features a negative ridged structure which under immense force imparts the ridges (millings) on the edge of the coin. It all happens very quickly and if a planchet isn’t positioned properly within the collar it results in an odd edge, usually a raised lip either partially or all the way around the coin. If a collar breaks completely, it can result in metal exiting the constraints of what should be the shape of the coin. Coins that are not round are more susceptible to suffering from partial collar problems and the new £1 coin seems to crop up a lot as a partial collar error coin.

A large type 50p that has suffered a slipped collar during striking.

6. Lamination errors …

Sometimes when the blanks are not properly prepared, fragments of flat metal can splinter off from them, either before the coins are struck, or afterwards. This can result in what appears as hollow areas on the coin’s surface or in thin bits of metal that appear slightly raised. This kind of error is not particularly common on UK coins, but usually it’s viewed as ‘one of those things’ and lamination error coins are mostly not that attractive. There are some more extreme cases which are more desirable.

7. Die clash or ghosting …

Both are caused by different issues, but can result in a similar effect on coins. The most commonly encountered of the two on modern UK coins is ‘die clash’, which seems to have affected a number of 2016 Jemima Puddle-Duck 50p coins and some 2017 Isaac Newton 50p’s. Coins with die clash have elements – often just outlines – of the design from one side appearing on the opposing side. e.g. with the aforementioned Puddle-Duck 50p, the obverse has a faint outline of the duck and the reverse has a faint outline of the Queen. It is the result of the two dies coming together at great force (with no coin-to-be between them) and partially imparting their images on to the opposing die. Ghosting, on the other hand, is caused by metal flow and is due to an imbalance of raised detail (or incuse detail on the dies) on each side of the coin. It was common on the early coins, particularly pennies, of King George V.

8. Slight tone differences …

Due to a number of possible causes (during manufacture and sometimes environmental conditions after a coin is circulated) coins can sometimes appear to be a different tone compared like for like. Some can have a streaky appearance, some appear much darker than normal. This can be curious and there are certain coins for which it seems to happen more often, but generally it’s not really viewed as a serious fault.

9. Dark ring on £1 …

A 2017 £1 coin showing the burnt-on dark rim around the outside of the silver coloured part.


Affecting mainly the new £1 coin but also some £2 coins – sometimes one or both sides have a dark coloured ring around the inner silver coloured part. This stain cannot be removed and is thought to be grease/gunk that was on the dies/planchet and has been burnt onto the coin due to the heat generated during the striking process.

An old 1960s florin with very weak lettering to the left of the Queen, almost certainly due to the die being filled with grease/crud.

10. Grease/crud blocked dies …

When excessive grease or other foreign matter gets into the dies it can lead to missing detail on the finished coin. The most common result from grease in the die is very weak or partially missing lettering on the coin.

11. Stripped plating …

Some UK coins are made of a cheap steel core, plated with a more attractive metal that is less liable to corrosion. Since 1992 the 1p and 2p are made of steel, plated with a very thin layer of copper. Coins have been seen where this thin layer of copper is missing, most likely they were made that way and the blank piece of metal was missing its copper layer when struck. 1p and 2p coins that are silver coloured (and magnetic) are a fairly common occurrence as error coins go. To add confusion, it is actually possible to strip the copper layer from a 1p or 2p without adversely affecting the steel core, and with a resultant coin which looks very much like it was made that way.

12. Corrosion bubbles …

1993 2p with a corroding steel core.

As mentioned above, the 1p and 2p are steel, plated with copper. The 5p and 10p also have a steel core and are plated with nickel to give them a nicer appearance. If the thin layer of external metal is compromised, dampness can enter and in extreme cases the coin can form large bubbles on the surface while quietly rusting from the inside out, which in the early stages can also resemble a die chip (see no.1). It is likely that contaminants were present between the core and thin plated layer when the coin was made, but it is also possible that the core has started to rust due to damage to the outer layer through use.

13. Edge lettering, words not properly formed …

Most commonly observed on the Guy Fawkes £2 coin, which in extreme cases can have edge lettering that appears to read ‘PEMEMBEP PEMEMBEP THE FIFTH OF NOVEMBEP’ (the R’s resembling P’s). The usual tabloid culprits made a big thing of it when it was first noticed and that resulted in people speculating and paying far too much for affected coins on eBay etc, before it all settled down. It is no longer considered a big deal, in fact Guy Fawkes coins with P’s instead of R’s are very common. The edge words are rolled onto the edge of the blank coin and what has happened is either the raised tails of the R’s were broken, or the edge lettering was too weak and/or the edge milling was too strong and parts of letters (e.g. the tails of the R’s) were virtually lost within the vertical edge milling. Similar problems are noted on other coins too; another that comes to mind is also a £2 coin with a weak/non existent ‘I’ in ‘Giants’ resulting in an edge that reads ‘STANDING ON THE SHOULDERS OF G ANTS’.

14. Queen wearing a necklace …

This is not an error at all, but is a rumour that still refuses to completely go away! In 1998 the Queen’s portrait was changed to the 4th portrait by Ian Rank Broadley, coincidentally during this time the new bi-metallic £2 was about to be introduced. Lots of new £2 coins were struck in 1997 featuring the previous portrait of the Queen, which happens to show her wearing a necklace, and lots were struck dated 1998 with the then new portrait of the Queen. Both coins were issued mid 1998 at about the same time and in those practically pre-internet days a rumour spread that the £2 coins with ‘the Queen wearing a necklace’ were in some way rare/special. I can remember my friend’s brother telling me that he was selling them to a bloke in his local pub for £20! He did well out of that, because they are worth just £2 face value.

15. Bi-metallic coins with lost detail in the metal join …

This isn’t really an error either, but is also something that comes up a lot. When a bi-metallic coin is struck, if everything isn’t set up perfectly central, or the shape of the outer ring and inner round bit isn’t exactly as it should be, it can lead to coins being produced with slight gaps on the surface between the two metal parts. This can often result in certain design elements being missing, e.g. the beads around the rim of the silver part or in more severe cases, elements of the main design. Two examples that come to mind are the 2006 Brunel portrait coin which often reads ‘TWO DOUNDS’ as the tail of the ‘P’ has been lost in the join of the two metals, or on the 2014 Kitchener WWI coin where the tail of the ‘Y’ from the ‘YOU’ above the date is also missing for the same reason. It’s unfortunate, but it is really down to the way the circulation coins are made at such speed and as such, there will inevitably be imperfections.

16. The edge lettering is the wrong way up …

No it isn’t! The edge wording orientation is completely random. It never used to be a thing and no one cared or even noticed it until the Sun reported (in one of the worst pieces of coin related journalism that I have ever seen) during December 2016 that the edge lettering should be the right way up when the coin is held with the Queen facing upwards. I have no idea where they got this information, but it was completely made up and even the Royal Mint must have been sick of the enquires as they published a piece online putting it straight.

More serious errors include:

17. Rotated dies (the more rotated the better) …

A 2015 Britannia £2 coins with a mirror reflection of its reverse which clearly shows that Britannia is almost upside-down.

It shouldn’t be possible, as the dies should be fixed in place and unable to move, but occasionally one of the dies that are used to strike the blank planchets into coins rotates slightly, resulting in a coin that doesn’t have the tops of each side in the same opposing position. Die rotation errors are very rare for pre 2008 coins, but are known to exist for certain modern coins. The more severe the rotation, the more desirable is the resultant coin and the most desirable die rotation error coins are ones where there is a 180 degree difference between both sides. As mentioned at the start, error coins are worth as much as people are willing to pay and values for die rotation errors can vary greatly from as low as a few times face value to hundreds or even (on very rare occasions) thousands of pounds, depending on the severity, rarity and how much people are prepared to pay to own it.

18. Clearly doubled lettering or other elements …

Doubled details, where some digits/letters or other design elements appear twice, one on top of the other but slightly offset, is most commonly caused by something known as ‘mechanical doubling’, or ‘machine doubling’. Mechanical doubling is caused when a coin is struck where there has been a simultaneous slight movement of a die, resulting in a double impression of design elements. Such doubling, although rare on UK coins, is considered a minor striking error and isn’t such a big deal in terms of desirability.

Even weaker, usually raised shadows or faint hints of duplicate detail around design elements (mostly letters and digits) that tend to extend towards the rim of the coin is often caused by die fatigue. This happens when dies are used beyond their normal working life – each coin they have struck has taken its toll on the surface of the die and the metal flow of the new coins, into the incuse die slowly wears out its detail. Worn dies that are not replaced can go on to strike many more coins with these shadowy features. This phenomenon is common and such coins are not considered valuable.

Part of the affected area on a 2010 technology £2 coin suffering from doubled lower letters. Picture from a post by manxcat12 on

Another much scarcer form of doubled detail is caused when a coin is struck from a die that has been engraved with doubled detail in the first place (often the doubling is not exhibited on the whole coin side). Doubled die coins are caused by a problem in what is known as the hubbing process, which is the early stage of coin production where master dies are created from a relief (positive, i.e. raised) impression of how the coin side should look. The hubbing process that imparts the incuse (negative) detail on the master die(s) doesn’t happen once per master die and it is these multiple passes that can, if there is a slight slippage or movement, result in a master die with doubled features. The dies should be properly inspected before they are passed onto the next stage of production, but when there is a movement and this goes unnoticed it results in coins being struck with areas of doubled detail. A recent example of this phenomenon occurs on the 2010 technology £2 coin, where the letters on the lower part of the obverse are very clearly doubled – this has been seen on a number of 2010 £2 coins so is assumed quite common.

19. Mismatched BU and circ dies (known for some gold coins) …

Something I have observed with some gold coins recently. The dies for proof coins and the dies for standard coins or for BU quality coins are quite different, even though they are of the same design. Proof dies are produced more carefully and (in recent times) have frosted raised details to contrast their mirror-like flat areas, which are known as fields. Other types of coin finishes don’t have such a contrast between the flat and raised parts. Coins with mis-matching sides in this way are caused by someone not paying attention and loading the machine with the wrong dies resulting in coins with one side inferior to the other. I seem to remember also hearing about this in connection with certain Pobjoy produced Isle of Man coins, too.

20. Fried egg £1/£2 collar problem …

A ‘fried egg’ error new £1 coin. Not all have a visible gap between the metals opposite the breach.

Basically bi-metallic coins that look a bit like a fried egg! New theory on this one, and it makes more sense to me: It could be due to the pill shaped middle (silver) part of the coin not lining up properly with the (brass) ring part just before it’s struck, causing it to be struck partially on the ring and not within it. This metal on metal means extra mass where it shouldn’t be and this is pushed out towards the edge. I used to believe this error was due to a rupture or breakage in part of the collar when the coin is struck (see also no.5), which causes metal to leave the normal parameter of the coin’s shape and this loss of metal in turn causes the inner round part of the coin to splay out and take it’s place. I’ve observed this quite often on the new £1 coin and on some 2015 £2 technology coins, and have also seen it on foreign (e.g. Euro) bi-metallic coins.

Some of the most serious (and valuable) error types include:

21. Withdrawn coins …

The withdrawn type 2011 Aquatic themed Olympic 50p.

Not strictly errors in the sense that something mechanical went wrong during production, but certainly a type of coin that is often quite valuable. Withdrawn coins are coins with designs that for some reason were produced (often in quite low numbers), then changed or improved upon and produced for the rest of the production run with a slightly different design. The best known example of a recent withdrawn coin is the 2011 Aquatics Olympics 50p – very early coins sold in packages featured a very different reverse with extra lines on the swimmer’s face. This was changed and most of the coins sold in packs and all of the coins that were circulated had less lines on the swimmer. Another example of a withdrawn coin is the recent Falkland Isles 1oz bullion coin produced by the Pobjoy mint – this coin was withdrawn because the Royal Mint took issue with it having the word ‘BRITANNIA’ featured on it, and they pointed out to the Pobjoy mint that no one apart from the Royal Mint is legally permitted to produce a silver coin featuring the word ‘BRITANNIA’. Pobjoy had to change it and released another version that completely omitted all wording on the reverse.

22. Brockages …

A brockage is a very rare type of error that is observed occasionally on much older coins. I’m not aware of any clear, complete modern decimal brockages. It basically happens when a coin is struck normally and fails to eject. The next blank planchet is inserted and struck with one normal die and on the other side, with the coin that previously failed to eject! The result is a coin (a brockage) which is normal on one side and has an incuse weaker version of the same design (transfered from the other stuck coin) on the other side.

The coin that originally got stuck in the die and failed to eject is known as a ‘die cap’ error. These are usually very expanded, a bit like a broadstrike (see also no.25) with an irregular shape. Die cap errors are very rare.

A 2002 UK territory 50p die cap error.

23. Double sided coins (often 1960s and shouldn’t be possible) …

Coins that are ‘double headed’ or ‘double tailed’ shouldn’t exist, at least not accidentally, as the obverse and reverse dies and machinery is usually made in such a way that the dies cannot physically be put in the wrong place, i.e. a reverse die cannot be exchanged for an obverse die. In almost all cases, doubled sided coins with the same design on both sides have been created by manipulating two normal coins and cleverly disguising the join.

I have never personally examined a genuine double-sided coin, but I am aware that my predecessor at Rotographic did list a couple in previous editions of the book upon which this website was originally based. The coins in question were from the late 1960’s or very early 1970’s and were most likely created deliberately by Royal Mint employees to test out dies or some other element of production.

24. Mules (human error) …

A mule is simply a coin struck from a mis-match of obverse and reverse dies, dies that should never have been used together but were, due to human error. Obviously such coins should be destroyed and shouldn’t find their way into circulation. There are a few modern well-known UK mule coins: the best known are probably the 1983 NEW PENCE 2p (made using the incorrect reverse die – it should have been the ‘TWO PENCE’ type introduced a couple of years prior), the dateless 20p, which was made in 2008 as a result of someone using the incorrect obverse die from the previous design 20p and very recently the 2016 new £1 coin where the incorrect reverse die was used with ‘2017’ micro dates around the edge (very hard to see without a decent lens). There are others including a 1994 gold proof £2 and a recent mix up with the dies for Lunar and Britannia silver bullion issues. The Isle of Man 1980 Christmas 50p with the incorrect obverse die that doesn’t state ‘Isle of Man’ is a non Royal Mint mule that also comes to mind. Not all mules are incredibly valuable though, as the usual demand and scarcity factors play a large role in obtainable values, with the dateless 20p and the mixed up silver bullion mules being of fairly low value due to high levels of supply in the case of the dateless 20p and fairly low demand for the mixed up Britiannia/Lunar silver issues.

25. Struck very off-centre …

Both sides of a very off-centre 2017 £1 coin.

Occasionally coins are seen that have been struck slightly of centre, evident from a thicker rim on one side and a thinner-than-normal rim on the opposing side. Such coins aren’t usually of high value. Coins on the other hand, that are struck very off-centre and are missing design detail are considerably rarer, they often look spectacular enough to whet the appetite of many error collectors and for that reason tend to be of much higher value.

Note that error coins known as ‘broadstrikes’ are also sometimes uncentred. A broadstrike is a coin struck without a collar, the lack of which results in metal spreading out to form a coin which isn’t perfectly round and is often thinner than normal.

26. Struck on wrong planchet …

My personal favourite and the type of error that I seem to be drawn to the most! A coin struck on the wrong planchet happens when a planchet prepared for a completely different coin, (or in the case of some bi-metallic coins – an incompletely processed planchet) ends up somewhere it shouldn’t be and is made into a coin. Bi-metallic coins (the £1 and £2) are potentially more susceptible to being struck on the wrong flan (or Planchet – it’s the same thing) as the manufacturing procedure is more complicated and where there are more stages, there is more potential for something to go wrong.

Bi-metallic coins are by nature, made of two pieces of metal. Normally a pill shaped central disc and a larger ring shaped piece are forced together at the same time as being struck with the dies that impart the design onto them. On rare occasions a ring shaped brass gold-coloured piece misses out on having a hole punched in it and manages to find its way in with the other correctly holed brass rings. I don’t know exactly how it happens and why the machines don’t notice that something isn’t right when an un-holed brass piece is rapidly inserted ready to be struck, but somehow it does sometimes happen and the result is a £2 or £1 coin made of a single piece of metal.

Other types of ‘off-metal strikes’ as they are sometimes known, are the result of a completely different blank intended for a different coin ending up somewhere it shouldn’t be and being struck with the incorrect dies to what it was originally intended to become. These incorrect planchets are often other types of UK coins (there is speculation that some of these may be deliberately created by mint employees), but as the Royal Mint also strike coins under contract for many other countries it’s very rare but can happen (proved below) that ‘foreign’ blanks end up in the wrong machinery and get struck as UK coins.

Note that other factors can result in coins that look like they have been struck on wrong planchets – very stained or externally corroded coins (e.g. due the coin being previously buried underground) can sometimes appear to be a completely different colour/metal and can be mistaken for a coin on a wrong planchet. Also, 1p and 2p coins that are silver coloured are often normal coins that are missing their copper plating, see no. 11.

Here are some examples of coins struck on wrong planchets:

A 2015 technology £2 coin on an all-brass (un-holed outer disc) planchet.


A 2008 50p struck on what appears to be (from the weight and magnetic properties) a one penny planchet.


A 2010 Florence Nightingale £2 struck on a foreign planchet (made of nickel plated steel), most likely one intended for a Gambian 50 Bututs.

27. Mixed denominations …

An incredibly rare type of error coin where a number of mishaps have occurred in the production process and have resulted in an already finished coin being processed again and struck as another coin or part of another (different denomination) coin resulting in a concoction that incorporates elements of two completely different coins. The examples described here are both mixtures of a £2 coin and a 50p from the same year.

The one shown below has been confirmed and guaranteed as such an error by the US third party grading company PCGS. What appears to have happened is that a finished normal 50p (the 2006 VC cross heroic acts coin, featuring a soldier) has somehow ended up in with the round brass discs that are normally holed to eventually make up the ring part of, in this case, the 2006 Isambard Kingdom Brunel £2 coin. The finished 50p has been holed along with the other brass discs and has moved along regular £2 production then been struck and combined with a regular pill shaped inner silver part into a £2 coin. As the 50p outer ring is slightly thinner than a £2 coin, it doesn’t show much of the £2 detail and still clearly shows ‘FIFTY PENCE’ from its previous existence as a regular 50p. However it does have clear elements of the chain reverse detail from the £2 coin dies. It has a slightly wavy rim which is milled but has no edge motto.

A 2006 £2 coin struck with an outer ring made from a finished 2006 50p.

The PCGS website image of the same 2006 £2/50p mix coin.

The other known combination of an outer ring made from a 50p and a £2 centre is a 2014 coin which features the centre £2 part of the Lord Kitchener coin and the outer 50p ring part from a standard shield-back 50p.

Authentication of errors …

This is not an error! This is the result of someone squashing two 10p coins together with a lot of force. The incuse ‘tails’ detail on this coin’s obverse is the impression made by the other coin.

With man-made post mint errors being common for certain coin types (particularly the bi-metallic £1 and to a lesser degree, the £2) and with Chinese forgeries of error coins also known to exist (currently of US coins, and as far as I’m aware none are known for UK coins) it’s understandable that some collectors seek official confirmation and correct identification of their suspected error coin. The Royal Mint do very kindly examine coins and return them, either with a letter describing the error (if the coin is a genuine error) or with a compliment slip and separate email to briefly describe the error. This is great (albeit usually a very slow process), but is unfortunately open to abuse for two reasons: 1. the coin that the letter relates to is not photographed, so theoretically the error coin that the Royal Mint examined could be swapped at a later date for a coin that hasn’t been seen at all by the Royal Mint and is not as described in the letter, and 2. The letters are on Royal Mint headed paper, but are fairly easy to replicate, in fact I’ve seen a fake letter claiming to be from the Royal Mint describing a very dubious looking error coin. In a similar fashion, screen shots or print-outs of emails can also be faked!

The Royal Mint have some highly experienced coin experts and have a lot of expensive equipment, but the letters they return with the coins are written by humans and they are not infallible – I’ve seen the text of a Royal Mint letter regarding a suspected error coin submitted by someone in 2015, where the coin in question had been, according to the Royal Mint, plated in nickel by someone post-mint, a conclusion that I did not agree with based on other factors, including the weight of the coin and other evidence relating to its appearance. There are some error coins that even people experienced with error coins don’t seem to be able to agree on!

The error coin industry in the United States is massive in comparison to the dealings with error coins in the UK (or Europe) and an alternative to authenticating errors via a Royal Mint letter is to send coins to one of the US based third party grading firms, the top two of which are globally recognised as having very high standards with regards to authenticating and grading coins. These companies, unlike the Royal Mint, do charge a fee for looking at and encapsulating (or ‘slabbing’) your coins, so it’s best to only submit coins for which you are 100% confident of them being a genuine error coin. Coins that are encapsulated are then guaranteed to be what they are labelled as if you buy any ‘slabbed’ coin (check the number and images online as there are known Chinese made fakes of foreign coins in slabs!) and can prove that it is not as described on the label then the third party grading company can be made liable for its cost.

As a general rule, serious error collectors do tend to have a very good understanding of the minting process and a combination of that and the experience gained from seeing or studying similar error coins, they can usually tell a genuine error coin from a home made ‘error’. Experienced error collectors will often buy, sell and swap with each other without the need of any kind of official authentication, trusting instead their own instinct and experience over above and beyond the knowledge of others.

Thank-you for reading this, any typos or other suggestions, let me know.

by CHP 16/12/17, with some corrections/additional information by Jason Renaud and some proof-reading by Laura Davis, Sarah Grant and Candice Clews.


The Check Your Change admin is Mr C H Perkins, publisher of numismatic publications in printed and eBook format. Author of "Collectors' Coins - Decimal Issues of the UK" and other books on British coins and related subjects.


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