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.
Posted by mnemtsas at October 18, 2009 2:06 PM
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