How can you tell if your coin is real or not ?
Beware rose coloured glasses
Ok, well hopefully the coin in question wasn’t an impulse buy! Clearly you need to be alert when you ‘just happen’ to come across what might be something special – the golden rule is that if it looks too good to be true then it is more than likely not what it appears to be.
You know, the ‘bargain bin’ contains a 1938 Aussie in amongst a whole heap of mostly cupro-nickel world crowns. Or in a selection of US Morgans, there’s an 1889 ‘CC’ mintmark – that sort of thing.
A true story…
Still, one time I was offered an album of Australian predecimal silver for not much above melt and when I looked at the threepences, there was a 1922/21 overdate…so I thought about it and pointed it out to the dealer asking if it was real or not…so he showed surprise, looked at it and said it’s a fake. The cynic in me says ‘of course he would do that’.
FoMO…..not worth it
Well, I didn’t buy that album – maybe I missed a trick, it might well have been a very valuable coin but my conscience is clear, I can sleep at night and if that dealer had actually overlooked several thousand dollars (pretty unlikely, but possible), then I figure I’m in his good books – certainly we’ve continued to do business and my feeling is that some good deals have regularly come my way, but that’s just me – others might look differently on the whole episode…
Small coins like that 22/21 3d are hard work just to look at…I mean there are some ways to pick counterfeits just by looking; say, if it had been cast then the details wouldn’t have the correct sharpness you get from a press and it might have mold marks from where the metal was poured…a whole lot easier to spot on something large, like a piece of eight!
In any case, I’d be very surprised if that particular threepence was real simply because it’s a prime candidate for being faked on account of its rarity. I think there’s only something like 900 known. Most of those are pretty heavily worn, too, so going by the level of detail is not the best approach to authenticate such a tiny piece.
It’s all about the mass
An easier and much more reliable method is to check the weight because fakes and counterfeits won’t contain enough nice, dense silver resulting in the piece being too light.
The weight is a pretty solid indicator – even for coins in low grade – since it turns out that real silver coins don’t lose a lot of metal through circulation.
R & D from the UK
We know this as a result of some terrific research, much of it readily available online.
For example, Kevin Clancy’s PhD “The recoinage and exchange of 1816-17” noted that British silver coins of the 18th century had been circulating for in many cases upwards of 80 odd years prior to the recoinage, with insufficient ongoing production that resulted in basically a whole lot of well used pieces of metal, almost no design left either side.
By the numbers
It turns out that coins which have gone through that amount of use have lost something like 20-25% of their original mass.
That’s a useful data point, despite such a worn coin not normally being desirable to a collector, it still allows us to pretty safely say that if a sterling silver coin is light by 20% or more, yet still retains some amount of detail – enough to be VG (F12) – then it’s probably a dud as it shouldn’t even have a readable date at that point of wear.
In addition if the grade looks to be VG (F12), then the coin ought to have weight loss in the region of 6%, meaning something in that condition with less than 94% of its official mass is a bit suspect.
Of course these are not hard and fast rules, just guidelines, but realistically very useful as mints have always been meticulous concerning the weight of their products. Certainly there will always be a slight bit of variation but they were everywhere and always careful to get it as precise and exact as possible.
Here’s what the coins actually look like:
Results from down under
Incidentally, it turns out that big coins wear more slowly than small ones – a coin fun fact that is also stated in another great piece of research, this one from the “Journal of the Numismatic Association of Australia” (Vol 23) – ‘Two 1921 NSW coin hoards’.
In this study by Bloom and Pitchfork, the coins involved were shown to be a true sample of what was then circulating in this Great South Land. Mixed in with 19th century British silver were Commonwealth of Australia coins from 1910-1921. Very interesting as the authors date the establishment of the stash around early 1921.
Anyway, back to the wear and tear… and just considering the Commonwealth (Australian) coins, the most worn coin type would be the oldest and smallest – the 1910 3d – and on average the loss was measured at only 2-3%.
The paper covers all the denominations, presenting the data as averages, however it does provide a simple formula for calculating the, let’s say, expected weight loss for each denomination – for the florin it is stated that:
2/- Mean Percentage Weight Loss = -0.1595 + 0.1833 x Age
Applied maths (useful)
Great! So let’s consider what it all means for the general, run of the mill 1932 florin because it’s the rarest and most valuable one and usually turns up in a lowish grade.
I’m going to say that our ’32 circulated for 34 years, so up until 1966 when decimals came on the scene and that this hypothetical coin was then put away in a drawer and left untouched.
Applying the formula gives a result of 6.0727% so that it lost that much of its original (theoretical) 11.31g, leaving us with 10.62g.
Also we’d be expecting VG (F12) for the grade as it’s a sterling silver coin and so would have been affected in a similar way to the British examples mentioned earlier.
You know, not too long ago I put up a 1932 in the coins for sale section of the site (…item# p46-448-1…)
Whatever…, it’s graded F (VF20-25) and I just whacked it on the scale then – here are the pics:
11.16 grammes.., well there you go, a pretty encouraging result really!
- K Clancy (Dec 1999) “The recoinage and exchange of 1816-17” PhD, University of Leeds, available online as a .pdf
- W R Bloom and C E Pitchfork (2012) ‘Two 1921 NSW coin hoards’ in “Journal of the Numismatic Association of Australia” (Vol 23)