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 Replies: 15 / Views: 1,973 |
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Pillar of the Community
778 Posts |
I have a very old coin which is made either of Silver or Platinum.
Where can I get it analyzed (non-destructively)?
Thanks,
Bill
Moved to World Coin forum - Sap Edited by BillSnyder
05/24/2012 05:57 am
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Bedrock of the Community
Australia
21786 Posts |
The cheapest way in the first instance is to post a picture and see if the 'Panel of Expert CCF Members' can help you out with an accurate identification.
If the coin has it's part in some sort of series, some info. may have come out of numismatic research. The next step may well involve a search on the 'Net.
At least in the first instance, such an approach won't cost you anything!
Taking it to a forensic lab, for an X - ray florescence analysis may cost more in fees than is practicable.
Actually my next door neighbour has such equipment in his rather large garage, along with two electron microscopes. I feel rather fortunate that I have such analyses done for free! He happens to have a pHd in materials analysis.
Edited by sel_69l
05/24/2012 03:00 am
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Moderator
 United States
14463 Posts |
you could check specific gravity of the coin. I don't know the formula for it, but you would just need to get its weight and volume.
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Bedrock of the Community
Australia
21786 Posts |
In this case specific gravity analysis will not help you. It IS certainly possible to obtain the specific gravity, the problem is that you can't compare the value you have found to a known coin alloy with it's specific gravity value, because the alloy of the coin has to be found first.
Mass spectrometry or X -ray florescence procedures are useful in determining the composition of the alloy. Once you have that, specific gravity values are not needed.
The cost of all the high tech. analysis that I have discussed, in my opinion, is not justified.
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Moderator
Australia
16826 Posts |
I beg to differ with sel, in the sense that, if the options are (1) pure or almost-pure silver, and (2) pure or almost-pure platinum, then specific gravity will certainly tell the difference between these two, since platinum is over twice the density of silver (it's denser than gold). A jeweller should be able to do an SG test for you, if you don't have the kit ot do it yourself.
I should also ask, exactly what is meant by "very old". Platinum coins and coin-like objects are basically unknown before 1800, since the technology required to work with platinum was not freely available before this. If you're talking something from the 1600s or earlier, than it isn't going to be made of platinum. Guaranteed.
Don't say "infinitely" when you mean "very"; otherwise, you'll have no word left when you want to talk about something really infinite. - C. S. Lewis
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Pillar of the Community
 778 Posts |
The coin is a copy, or perhaps a test piece, of a Russian 1832-cnb 12 Ruble. As you see, one side is a nicely rotated double strike, but the other side is almost a caricature of the real design. I understand that this series was made back when platinum was merely a bi-product of the mining industry back in the Ural Mountains. The coin is about the right diameter (about 36mm), weighs 13.79gm (vs a normal 41.41), is very thin, and rings like a bell. The edge has this design - ////////////// I understand that a balance capable of reading to 4 places is needed to do a specific gravity test. (My top-loader only reads to 2 decimal places). Also, I very much doubt that the Platinum used at that time was any where near pure. Here is the actual piece -   Thanks for your help, Bill |
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Pillar of the Community
Australia
7096 Posts |
 with Sap on this the sg on silver is way lower than on platinum |
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Bedrock of the Community
Australia
21786 Posts |
If it is a copy, it could be of ANY alloy. You can get to the density right enough, Sap is right if it is either Ag or Pt but if it is an alloy, of unknown type, the problem is harder to solve.
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Moderator
Australia
16826 Posts |
Quote:
The coin is a copy, or perhaps a test piece, of a Russian 1832-cnb 12 Ruble. As you see, one side is a nicely rotated double strike, but the other side is almost a caricature of the real design. I vote copy, mainly because of the crudeness of the obverse. In 1832, they had plenty of experience with striking platinum - there'd have been no need for test pieces. Quote:
The coin is about the right diameter (about 36mm), weighs 13.79gm (vs a normal 41.41) That right there screams "fake". And probably not platinum, either, though it might still be worth checking. Quote:
Also, I very much doubt that the Platinum used at that time was any where near pure. Oh, but it was, as pure as early 19th century technology could make it. Certainly the density should be near enough to the book value of platinum to easily tell the difference with SG. I suspect it isn't platinum, just because of the discolouration (platinum isn't supposed to go like that, to my knowledge) but I suppose it could have been made from a piece of "scrap" platinum from a chemical reaction vessel; that might explain the thinness and discolouration. SG will tell whether it's platinum or not, but the "or not" could be pretty much anything else, not just silver. I'm not convinced platinum and silver are the only possibilities for this object. Don't say "infinitely" when you mean "very"; otherwise, you'll have no word left when you want to talk about something really infinite. - C. S. Lewis
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Pillar of the Community
778 Posts |
Hence my request for a metal analysis. <grin>
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Pillar of the Community
United States
2605 Posts |
Quote:
I vote copy, mainly because of the crudeness of the obverse. Crudeness of everything! Look at the "denticles" (if you can call that mess denticles). Look at the letters, numbers! Overall design is well inline with "almost a caricature of the real design". Nothing is real about this piece. They started striking it in 1830, there wouldn't be any "tests" in 1832. I vote a badly executed forgery by an aspiring amateur. I wouldn't expect any value in it. |
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Pillar of the Community
Australia
3831 Posts |
Bizarre - that's all I can say. I remember reading somewhere that the manufacturing of such platinum coins were actually quite different from what I imagined. It was in the form of a sponge / powder form instead of forged and stamped. This might be of something interesting to read: http://heraeus-ptcomponents.com/med...Platinum.pdf |
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Moderator
Australia
16826 Posts |
Because platinum basically doesn't melt, not with early 1800s technology anyway, they couldn't melt the raw platinum and pour out bars or ingots, as is done with gold and silver. But platinum can be cold-forged. The raw platinum was first refined chemically, which creates a fine powdery form of pure platinum known as "sponge". To make the blanks for the coins, they compressed the sponge powder into solid metal in a press, then these blanks went into another press with the coin dies in it for actual striking. As I understand it, much the same technique is still used for modern bullion coinage.
Don't say "infinitely" when you mean "very"; otherwise, you'll have no word left when you want to talk about something really infinite. - C. S. Lewis
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Bedrock of the Community
Australia
21786 Posts |
Sap: That being the way Pt is, I would think mints around the World would order blanks in from an outside supplier, to feed directly into a coining press.
As I understand it, that already happens at the RAM with Al bronze blanks anyway, and for bi metallic blanks for other mints.
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Pillar of the Community
2223 Posts |
Send it to Sel, I'm sure he'll walk it over to his neighbor with a bottle of beer.  |
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Pillar of the Community
United States
1757 Posts |
Contact me privately. I can do for $50.00 a full XRF analysis. This includes the P&H and a registered return with insurance. So the analysis will cost you $40 or so ... See my company: http://www.edax.com Platinum as P.T. Craddock informs us was readily available in this period in Russia and South America. We normally see platinum for gold contemporaries of the 19th Century as a mix of gold and platinum. John Lorenzo United States |
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Replies: 15 / Views: 1,973 |
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Posted 05/24/2012 03:22 am
