READ THIS! The Next Generation Of Chinese Counterfeits Have Arrived

Discussion in 'US Coins Forum' started by LostDutchman, Apr 25, 2015.

  1. LostDutchman

    LostDutchman Under Staffed & Overly Motivated Supporter

    Yes, This form of assay goes completely through the sample, or so I'm told by the refiner.
     
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  3. -jeffB

    -jeffB Greshams LEO Supporter

    Well, it's hard for me to understand how it could not be thrown off by surface composition, but I'm certainly in no position to tell a refiner how to use his equipment. :) Time for me to put down the speculator!
     
  4. LostDutchman

    LostDutchman Under Staffed & Overly Motivated Supporter

    The quick and dirty way it was explained to me was it sends x rays through a sample and a sensor opposite the x rays measures deviations in the x rays and from that the machine can tell the composition of the piece.
     
  5. -jeffB

    -jeffB Greshams LEO Supporter

    Ah, OK. The machines I'd read about all seemed to work by reflection or fluorescence, not by absorption. As you can probably tell, there's a lot I don't know about the machines. :)
     
  6. sgt23

    sgt23 Active Member

    Why do they not test the coins for age? This is what archaeologist do.
     
  7. -jeffB

    -jeffB Greshams LEO Supporter

    I think the analyses archaeologists use aren't that simple, certainly aren't very cheap, and don't do so well at distinguishing how many decades old a coin is.
     
    sgt23 likes this.
  8. sgt23

    sgt23 Active Member

    I wonder if pollutants on a coin could be measured? China and Bulgaria aren't know for being cleanest places on earth.
     
  9. Numismat

    Numismat World coin enthusiast

    Archeologists can date organic compounds, not inorganic things like metal. They can only test the age of organic compounds on the surface of a coin.

    If they could radio-carbon date coins, forgeries of high end coins would not exist.
     
    sgt23 likes this.
  10. GDJMSP

    GDJMSP Numismatist Moderator

    The precious metal content of a counterfeit being what it is supposed to be is not unusual. There are many, many counterfeits, both gold and silver, that have the correct precious metal content. Some are even known to have too much. But the trace elements, that can be a pretty good tell. And in fact some counterfeits are identified by their trace elements, or the precious metal content being too high.

    This is why weight and diameter alone cannot be used to definitively identify a fake and that design diagnostics must be used to identify them. This has been the case for centuries. A good example of that would be the counterfeit Netherlands ducats minted by the Russian Royal Mint in the 1700's and 1800's. It got so bad that the Netherlands mint even stopped minting ducats and sent an official diplomatic request to the Russian government asking them to stop minting counterfeit Netherlands ducats and stating that they would not mint any more of them until the Russians stopped.

    And to illustrate just how good those Russian fakes were, even today the TPGs are still fooled by them and they slab Russian fakes as being genuine Netherlands ducats. The same kind of thing has happened with counterfeit Morgan dollars, they were so good the TPG slabbed them as genuine, only later to discover they were not.

    And unless I am mistaken this is the point Matt has been making all along. The counterfeiters have been good for a long time, but now they are even getting better. Good enough to fool the TPGs too ? Dunno and can't say. But it has certainly been done before, and still happens, today, with Netherlands ducats that were minted almost 200 years ago.
     
    micbraun, imrich and Numismat like this.
  11. Conder101

    Conder101 Numismatist

    I would be highly suspect of this claim. X-rays typically don't penetrate metals too well unless they are low density metals or very powerful X-rays. Normally these X-ray composition tests only test a short distance into the sample.

    The sensor is on the opposite side of the coin from the X-ray source? If that is true it could be a high power X-ray source. It would be interesting so see how it reports a 40% silver clad half dollar.

    Usually these composition detection devices work by re-emission. The initial X-ray exposure excites the atoms. As the atoms return to the lower resting state they re-emit X-rays with each element re-emitting its own characteristic frequency. The frequencies present tell you what elements are present and the relative strengths of each frequency tells you the percentage composition of each element.

    "Ring" tests are NOT a very good authenticity testing method. Way too many variables that can affect the results, and interpretation of the results is questionable
     
    Coinchemistry 2012 likes this.
  12. Vess1

    Vess1 CT SP VIP Supporter


    You hit the nail on the head. He could have posted this in a different thread and asked for a grade and everybody would have started grading it. One or two people, maybe, MAYBE would have mentioned questionable authenticity. Then they would've been laughed out of the thread. "It's just a common quarter after all. Who would counterfeit that?"

    I think it's a difficult road trying to convince some collectors that these are appearing out there. Some don't want to believe it or accept it.

    Since it was presented as a counterfeit to begin with, everyone is an expert on it and it is spoken of as matter of fact in every post. Certainly an eye opener. Would fool enough people to make all the money they want without tweaking any further really.
     
    Paul M. and imrich like this.
  13. imrich

    imrich Supporter! Supporter

    Is it true that a portable XRF analyzer is an inaccurate tool for content analysis of coins?

    I was to understand that is a proven preferred reliable tool for on-site non-destructive testing.

    I'm still questioning/learning, as I don't know when I'm misinformed.

    JMHU
     
  14. Conder101

    Conder101 Numismatist

    I think it is a good tool, but we need to know exactly what its limitations are. Now deeply can the analyzer read into the surface? How does that change based on the density of the material being sampled? (I would expect the higher the density the shallower the reading.) I know they can read through slabs (plastic is low density) but the further the reader is from the surface being read can affect it in what way? How large an area does the analyzer actually sample?
     
  15. imrich

    imrich Supporter! Supporter

    I believe if you internet query "non-destructive coin analysis", you'll see a tool where I believe the device could scan any normal coin.

    JMHO
     
  16. Conder101

    Conder101 Numismatist

    Nothing comes up with that search. Search for portable XRF analyzer turns up many examples they all use the re-emmission method of element determination so they are most likely not just a surface reader but none of them give information on depth of penetration but most likely they do NOT go all the way through since the source and sensor are on the same side. Only one made any discussion of the size of the sampling area. It was adjustable with a sample area of 3, 5 or 8 mm in diameter.
     
    imrich likes this.
  17. Numismat

    Numismat World coin enthusiast

    @Colonialjohn should be able to clarify exactly how XRF and similar methods work
     
  18. LostDutchman

    LostDutchman Under Staffed & Overly Motivated Supporter

    I spoke to a representative about purchasing an XRF gun. I was told by the rep, in person, that it only penetrates 5 microns into the surface. That does me no good. I'll stick to my acid tests.
     
  19. LostDutchman

    LostDutchman Under Staffed & Overly Motivated Supporter


    I'm no expert on those machines... this is how it was explained to me by someone in the industry. I'm not sure if completely accurate or not.
     
  20. lucky43113

    lucky43113 Active Member

    those xray guns are expensive ones i saw were around 30k showed a break down of all the elements in the "coin" being tested
     
  21. spock1k

    spock1k King of Hearts

    this is nothing compared to what they have done for some indian rare coins. we are close to the point of declaring all specimens illegal of certain coin types
     
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