X-rays join the fight against fakes [Coin News, August 2009, Page 50]
by Brett Hammond of TimeLine Originals
One of the major problems for any dealer in manufactured items is getting the description right – whether the objects are expensive watches, motor vehicle parts or designer-label garments at ridiculously low prices. A stroll through any street market will provide plenty of evidence for ‘fake’ or misleadingly described goods. Not everything is what it appears to be, and the old Roman tag of ‘caveat emptor’ (let the buyer beware) has never been more apt.
In the field of coins and antiquities there is plenty of scope for mistaken or misleading descriptions. The rewards for passing off modern fakes as genuine ancient coins can be very tempting. At TimeLine Originals we have to be very careful never to offer for sale as genuine an object which is in any way ‘dubious’. This means that any items we place on our website have been thoroughly researched, which is a very expensive and time-consuming task, but an absolutely essential one if our customers are to be able to buy from us with complete confidence.
Research can mean several hours spent poring over reference books and archaeological reports, looking through back-issues of metal-detecting magazines and auction catalogues. The cost of this research can never be recouped through the sales price of the articles, but the cost of not doing enough research is that fakes remain in the market, the forgers are encouraged to continue and collectors cannot be sure that the coveted items they buy are genuine.
But modern science can assist with weeding out fakes and forgeries. There have been many developments in dating techniques since the beginnings of science-based archaeology in the mid-20th century. Thermoluminescence, dendrochronology and carbon-dating are three of the better known techniques. More recently, X-ray Fluorescence (XRF) has been added to this list.
The principle behind XRF is quite simple: the coin’s surface is bombarded with X-rays; these interact with the metal at the sub-atomic level, making it fluoresce (glow) and the wavelengths of the fluorescence are measured by the machine. The fluorescence pattern is different for every element present, so an accurate analysis of the composition can be made. The recent development of portable machines which can display the results on an integral screen is the real breakthrough – instead of having to take the sample into a controlled laboratory environment, prepare it and wait for the results, with modern machinery and computing power it is possible to discover the relative proportions (percentages) of the various elements present within a matter of minutes.
What this means for coin and antiquities dealers is that it is no longer necessary to rely on subjective judgements when evaluating an article. The look and feel are still important, but with XRF technology it is possible to add to these the results of objective analysis, to add defined quantities into the equation.
Because XRF testing is completely non-destructive, it does not damage the coin’s surface or even disturb the patina – the X-ray penetration is just a few atoms deep, totally invisible and without any effect on the article itself. This is especially useful when a highly sensitive and rare piece has to be evaluated – a few minutes with the XRF technician can provide objective data which can not only spot whether it is a fake or not, but can actually give impartial information to back up the technician’s opinion based on the test results.
Oxford X-ray Fluorescence (details below) is a new company offering just this service, which we believe will become increasingly commonplace among antiquities dealers and collectors. For a minimal cost and delay, an object with a price tag of hundreds or thousands of pounds can be evaluated. For the collector, this is a sensible investment of time and money – especially where so much is at stake. Not only does a fake coin in a collection call into question the reliability of the dealer from whom it was purchased, it also raises queries about the judgement of the collector who accepted it!
Obviously, the XRF test results do not in themselves show an object to be genuine or false. The technician has to have some known genuine results with which to compare those from the piece being tested. It is necessary to build a database of such results, and to keep it up-to-date. The database provides the yardstick against which the coin is to be measured – and the degree to which it conforms provides the level of confidence for the piece. Therefore, typically the outcome will be expressed in such terms as ‘compatible with a Late Roman date’ or ‘consistent with results for the Tudor period’.
As XRF testing is rolled out among collectors and dealers, the spotting of many fakes will become much easier. This will no doubt cause the serious forgers to raise their game in order to circumvent the new technology. But for the majority of forgers it will cause insuperable problems which will make the enterprise unrewarding and thus unattractive. If collectors’ confidence in their purchases through reputable dealers is increased, this will in time drive out both the fakers and the dealers who do not ask too many awkward questions.
TimeLine Originals have been using the Oxford X-ray Fluorescence testing for some time and have been more than satisfied with the results achieved. For collectors and dealers wishing to learn more and to try out the service, the website of Oxford X-ray Fluorescence Ltd can be found at http://oxford-labs.com where details of the process and costs of testing are explained. They can be contacted by email email@example.com.
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