Recently in Error Coins Category

1964Y Penny Struck Through Wire or Cotton

The strike through or strike thru error term is given to an error observed on a coin where there is an incuse marking on the coin that looks as if there was something on or adhering to the coin surface at striking. This might me a piece of wire, metal or a piece of string or grease or some other foreign material. On occasions the foreign matter may still be stuck to the coin!

During cleaning or maintenance of the coin press, oil or grease needed to maintain the presses mechanical activity may get onto the surface of the die. If a coin is struck though oil then the resulting coin will have the appearance of a missing piece in the design or a poorly struck surface. It is also termed filled die or struck through grease filled die. This is often more impressive on a coin missing important features such as a letter in the date or even the entire date. The effect of a strike through oil may have the appearance that the surface (in that area) has been harshly cleaned or machined down, this is becasue of the texture of the foreign material and the concave impression it gives to the coin surface.

It is common to find coins struck with greasy or even rusty dies resulting in poorly struck surfaces, features or legends. This is really just poor quality control from the mints resulting in poor quality coins rather than collectable error coins. If the strike through is spectacular then expect a premium price for the coin.

196? Penny Struck Through Oil

There was an example I have seen of a strike through red cotton on the coin surface and the resulting struck coin still had the piece of red cotton attached! Fitters who work on the presses at the RAM use red rags to clean the presses and die surfaces. Seen in one of our previous articles are the fitters changing the dies on the gallery press and the red rag in use for clean up (see top image in link).

Australian 1933/2 Overdate Penny

A particular type of coin variety is the overdate. Put simply an overdate is a coin struck from a die that has a trace remnant of a previous years numeral in the date. Among Australian copper and silver Commonwealth coinage there are 4 known overdate issues, the 1922/1 3d, the 1925/3 1s, the 1933/2 1d, and the 1934/3 3d. The image above shows the 1933/2 overdate penny with the last 3 of the date expanded. You can see clear traces of the underlying 2 extending from the end of the top loop of the 3 and from the front and back of the top loop of the three, There are a number of overdate issues available among the gold Commonwealth issues of the 19th century. As far as I understand there are 3 different ways that an overdate working die can be produced:

1. A master die or punch is re-worked to show the new date and traces of the old date remain when working punches are produced from the masters.
2. A working punch is reworked to show the new date and traces of the old date remain when working dies are produced from the working punches.
3. An existing working die is re-engraved, re-punched, or hand stamped to show the new date and traces of the old date remain when coins are minted from the die.

Looking at the Commonwealth overdate issues and their relative mintages it isn't hard to postulate how each issue was produced. The 1922/1 3d is an extremely low mintage coin, less than 1500 issued so may be the product of just one re-worked production die. The 1933/2 penny and the 1934/3 threepence comprise just a fraction of the total mintages for the year but enough to suggest that one or more overdate working dies were produced and used to make coins during those years. Jon Saxton at Triton Coins suggests that the 1933/32 penny working dies were formed by hobbing existing 1932 penny working dies with a 1933 penny punch. He goes onto suggest that a similar process may be responsible for the entire 1925/3 shilling production. Jon also has an excellent description of how the 1922/1 over date threepence die may have been produced which you can read here.

Australian 1925/3 Overdate Shiling

Above you can see a 1925/3 overdate shilling. The overdate on these can be a little difficult to spot but if you look closely at the expanded 5 of the date you can see the end of the top loop of the 3 protruding from the top left of the 5.

The Royal Australian Mint in Canberra displays a wide range of coins in their museum on the first floor of the newly refurbished building. Amongst the coins on display is a variety of error coins or mistakes that have happened to coins during production. We're lucky to have some of these coins on display because it's quite rare that coins of this nature would pass by the strict quality control to exit the mint and enter circulation.

The 20 cent proof shown below is one of those coins that jammed the machine and was never capable of exiting the press. One of the feeder fingers which feeds the blanks into the press has malfunctioned and the pressures of the strike have welded the feeder finger to the coin. The press would have needed to be dismantled to fix this coin jam.

Major whoops 20c Proof

The Australian commemorative dollar shown below is termed a "die cap". It failed to be released from the press, adhering to the upper hammer die. It was this "capped" coin that struck the subsequent coins. The blanks fed through while the cap was in place struck on this die cap and would exit the press as brockage errors showing the mirror image of the design on the reverse. The more brockage errors the die cap strikes the higher and deeper the cap becomes before breaking from the hammer die.

2009 Citizenship $1 Die Cap Error

We've spoken before about double struck coins and this example is a beautifully toned magnificent example of a double struck 10c. A struck coin failed to eject from the press completely and was struck for a second time. This produced an elongated planchet with half of the coin design depicted twice.

10c Double Strike

It's been more than a year since we wrote our first article on coin errors and we thought it was worthwhile creating an article covering each and every error we've written about. It should make for a handy reference spot from which to find information and helps to bring a couple of dozen articles into one location.

Brockages

Brockages
Brockages of Australian Coins

Clipped Coin Errors

How to Determine a Genuine Clipped Coin Error
Clipped Planchet Error Coin - Straight Clip
Curved Clipped Planchet Error Coins
Double Straight Clipped Planchet Coin Error Part 2
Double Straight Clipped Planchet Coin Error
Double Curved Clipped Planchet Coin Error
Elliptical Planchet Error Coin
Outward Curving Clipped Planchet Error Coin

Double Strikes

Rotated Double Struck Coin Error
Double Struck Coin Error

Errors Due to Collar Problems or Planchet Location Problems

Australian Broadstrike Errors
Off-Centre Coin Errors
Out of collar or Partial Collar Coin Errors
Ramstrike or High Lip Coin Error
Australian Indent Errors

Errors Due to Planchet Flaws or Impurities

Peel or Lamination Flaw Coin Error
Australian Split Planchet Errors
Split Planchet Errors Part 2
Split Planchet Errors Part 3
Strike Through Error

Other Coin Errors

The "Upset" coin error.
Double Errors
Rare Australian Decimal Coins: Part Two- Extreme decimal rarities
The Mule Coin Error
The 2000 $1 / 10c Mule
Clashed Die or Die Clash Coin Error
Coin Cuds or Die Chip Error Coins
Wrong Planchet Error Coins

Picture this, you get some change from the local Subway after buying some lunch, and you look down at your change to see if there's anything valuable or unusual in your change (you do look don't you?) and something catches your eye. That 20c piece has two heads! You've just struck it rich, a coin worth thousands found in your change! Or have you? Sadly, almost certainly not. Genuine double headed or double tailed coins do exist but firstly they are very rare, and secondly the chances of one ending up in general circulation is almost nil. Why? Well because by the very nature of the way coins are made the chance of a coin being minted by accident with two obverse or reverse dies are basically nothing. In the US mint for example it is actually impossible to fit a reverse die into the obverse side of the coin press and vice verse! Don't get me wrong, these 'errors' do exist but in Australia they are due to mint production staff deliberately installing two reverse or obverse dies into a coin press and making a few 'error' coins. I imagine that most of the time these 'errors' are destroyed but sometimes by means fair or foul they get onto the market for collectors to obtain. The chances that these trials (or perhaps errors deliberately made to sell) ended up in general circulation coins for you and I to spend are therefore minuscule. A genuine double sided coin in pristine uncirculated condition can fetch from $2000-$4000 at auction depending on the denomination of the coin.

OK let's get back to the fake double headed or double tailed coins. These do exist and are not too hard to find. This is apparent by the fact that we have many questions from the readers of this blog about double tailed/headed coins that they've found or have been in possession of for some time. We'd say that out of all the questions we've had about this type of coin, that exactly one may have been genuine. The first reason is that almost all of them have been heavily circulated and as I mentioned above these coins just would almost never get into circulation. The second reason is that with a genuine double headed/tailed Australian coin the two sides are always 180 degrees rotated from each other. This is because of the way dies are designed, if you put an obverse die into the reverse side of a coin press it will be rotated 180 degrees and the same thing happens with the reverse die. So what are these fake errors called? The most common name is a magician's coin. So how are these coins made? I am aware of a couple of methods which you can see below.

Making a Magicians Coin - Method 1

The first and most crude method (shown above) is to simply take two coins that are the same and cut the coin in half through the plane of the coin and then stick the two sides together. This could be done on a milling machine or lathe by any reasonably competent person. The main problem with this method is that there will always be a visible seam around the edge of the coin.

Making a Magicians Coin - Method 2

The second (and more common) method is illustrated above. One coin is cut in half and then the rim removed from that half. The other coin has the same part of the coin machined out with precisely the same diameter as the first part with the rim left intact which provides a cylindrical receptacle for the first part. Both of these operations could again be carried out with a lathe or milling machine and if the tolerances are fine enough the two parts can be fitted together with a barely perceptible seam in a corner. This machining operation is a little more difficult to perform and I can only wonder that more of these types of fakes are around because they are presented as challenge pieces to apprentices to test their skills on their machines!

There we have it, double headed/tailed coins, how to determine if yours might be a real one, and how the fake ones are made. If you've got a coin that you think is real then by all means take it to a coin dealer and let them take a look at it. It's usually very hard to pick well made fakes from a photo so having the coin in hand may well be the only way to determine if a coin is real. Even then more rigorous inspection techniques may be required to determine a genuine error from a truly skillfully made fake, this may include a dye penetrant test or even x-raying the coin.

We've looked at all the diffrent types of clips before and how they've occured but how can you really tell if you have a genuine clip or not?

Often it is difficult to tell if a clip is a genuine error from the mint or if someone has simply used a guillotine or tin snips to manufacture the defect. There are a few distinguishing features that will help you determine a genuine coin clip. A genuine clip will show at least one of these effects.

1. The Blakesley Effect: named after the American numismatist who first described this defect. It occurs as a weakness on the rim opposing the clip site. This only occurs on coins in which the planchets have been pre-rimmed before striking. Coins that are rimmed during the striking process of the coin such as the Australian 50c will not show the Blakesley effect. You can see an example of this effect in the right image outlined in red below.

2. Fish-Tailing: is a deformation of the lettering in the legend or on the design around the clip site. Instead of the edges of the letters being straight, they have an inward lip and the metal has flowed outwards at the edges. Due to the incomplete planchet (the clip) the metal has not been contained during the striking so the edges of the letters or edges of the design have fish-tailed outwards. This will occur on the lettering or on any part of the design near the clip site. Often this might only be distinguishable under magnification, the image below left has been highlighted so you can see the fishtailing affecting this halfpenny.

3. Strike Weakness: will sometimes occur near the clip site. This is due to the planchet being slightly thinner on the edge at the clip. Because of the missing metal it will flow into the void creating a weak strike or a weakness in the area near the clip. This is clearly shown in the image below left.

A genuine 1961 halfpenny clip showing all 3 effects (highlighted in red)

Australian 2001 Centenary of Federation Dollar - 9 o'clock upset

An upset coin is produced during minting when the dies for the reverse and obverse of the coin are not aligned correctly.

For Australian coins if you hold the reverse of the coin upright with a thumb and forefinger on the top and bottom edge you should be able to rotate the coin around to view the obverse which will be upright also. Australian coins are minted with what is known as 'medal alignment'. Coins from other countries (such as the USA for example) mint their coins with what is known as 'coin alignment'. When
if you hold the reverse of a 'coin alignment coin' upright with a thumb and forefinger on the top and bottom edge you can rotate the coin around to view the obverse which will be upside down (in contrast to Australian coins).

A regular coin should have the Queen (or King) look at you straight on. During minting one of the dies might not be aligned correctly or might rotate during the production run. When turning the coin around, if a coin is an upset it will show the obverse (Queen's side) facing anything but upright. She may be leaning over to the right 90 degrees (a 90 deg upset) or upside down (180 degree upset). You may find these upset errors in any number of degrees of the clockface.

If one side of the coin is only rotated a small amount, up to say 15 deg (or 1 o'clock) it won't be considered an upset. This angle may be considered normal as there is a small allowance for slight angle movement in the struck coin. Pre-decimal coins may often have a slight degree of upset which is considered normal which is not so common in decimal coins.

During one production run of 2001 Centenary of Federation Dollars at the Royal Australian Mint in Canberra this error occured. Collectors have found varying degrees of upset coins ranging the entire clockface from 1 degree to 359 degrees. In this case during only one production run the obverse die rotated throughout the run causing the varying degrees of upset.

An upset coin will demand a premium over it's regular counterpart. The degree of upset will also determine how collectable it is. A Federation $1 upset pulled from circulation with a 90 degree angle may fetch $20 or more depending on it's condition so it's worth looking out for this error in your change. It is also a coin that is not impossible to find! These Federation upsets are the most common upset coins to find. Any other upset of another denomination or a pre-decimal upset with a high rotation will certainly command a higher premium as they are much less common..

Australian 19?? Half Penny - Rotated Double Strike

Previously we talked about double struck coins errors but this entry largely covered double struck coins where the coin had been struck once and then partially left the coining chamber before being struck again. This results in two clearly visible strikes to the coin, with one partially overlapping the other.

There is a slightly different class of double struck coin known as the rotated double struck coin. This error occurs when a coin is struck and is ejected from the coining chamber but the struck coin falls back in the coining chamber. It is then struck again but the coin had rotated slightly so the result is two strikes to the coin that are rotated with respect to each other.

Above you can see an Australian half penny of indeterminate year that has been struck twice. You can see the results of the first strike clearly, with the second portrait visible at about 45 degrees to the correctly oriented portrait. You can also see a second kangaroos tail at 45 degrees to the first on the reverse of the coin. It appears that this coin rotated about 45 degrees counter clockwise (viewed from the obverse) when it was struck the second time. The second two figures of the date in both strikes has been obliterated by the other strike so it's impossible to say what year this coin is.

Australian 1964 Penny - Rotated Double Strike

Above is another rotated double strike. This time it is an Australian 1964 Penny. This coin has rotated nearly 90 degrees clockwise (viewed from the obverse) after the first strike. You can see this clearly on the reverse with the first set of kangaroo front legs emerging from the hind legs of the second strike. It's not entirely clear in the image but you can also see the ribbon on the back of HM's hair from the first strike in the middle of HM's head from the second strike.

We've spoken before about broadstrike error coins. There can be varying degrees of a broadstruck coin and as the size of the error increases it becomes an off centre strike. These off centre strikes are probably the most common and well known of errors as they are often very obvious and can be very spectacular errors.

Australia Threepence Off Centre Error

This type of error is a massive variation on the out of collar error. In this case the blank is not fed into the press properly and lands in the collar incorrectly. For the off center strike only part of the blank is struck by the upper and lower dies. This results in only part of the design being struck on the coin and a coin that is not it's usual round shape. Because of their unusual shape they are commonly picked up before they leave the mint or in rolling machines by security companies. They are most often explained as their % amount off centre.

Australia $1 1985-1991 Mob of Roos Off Centre Error

Australia 1967 20c Clipped Planchet and Partial Collar Error

One thing you don't see too often when you're looking at error coins are coins with two errors or double error coins. They are rare enough that if you're at all interested in collecting error coins that you should snaffle up double error coins whenever you happen to see one. In my time collecting and looking at error coins I can recall seeing exactly 4 double error coins. I dont count double clipped planchet error coins as double error coins as they are really just a class of clipped planchet error.

The double error coins I've seen are a clipped blank planchet (it's questionable whether a blank planchet is an error anyway), an indent error with a partial collar, and two clipped planchet errors with partial collar errors. I'm lucky enough to own a few of these double errors that I've seen including the last one, the clipped planchet with a partial collar error.

You can see this above, an Australian 1967 20c coin with a large clipped planchet and the corresponding weakness in the rim opposite the clipped area. The is a tell tale sign of a true clipped planchet, the so called 'Blakesley Effect'. As a clipped planchet error this is a lovely example, the coin is a nice high grade. However, to top it all off the coin is ALSO a partial collar error! The 'railroad' rim is obvious on the coin edge, with the reeding imparted by the collar only going half way down the edge of the coin. This shows that the coin was only partially engaged with the collar when it was struck.