Question about US Gold coin collecting

thank you

 

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At your age get the hard ones first. Then think of starting a family

 

When your somewhat older. You can focus on choices that where made in the past Know what It’ll fun

 

thank you

 

Doug,

If you read the PCGS article on the sniffer, it describes energy-dispersive X-ray spectrometry (EDX) as one of the techniques it uses. EDX is a more generalized term than XRF (x-ray fluorescence). In EDX, atoms of the test material can be excited by any means to emit x-rays, which are analyzed to determine the elements they came from. The two general means of excitation are EMR (electromagnetic radiation), i.e. gamma rays or x-rays ... and x-rays are the usual choice ... OR ... particle bombardment ... electrons in a scanning electron microscope (SEM) are the usual choice. XRF is EDX where the means of exciting the atoms in the test sample is x-rays. Compact XRF units resemble a gun, but some are the size of a car. The larger units can probe more deeply into the sample, focus on smaller areas, and may have automated sample handling as well.

The sniffer almost certainly uses an XRF form of EDX. Using a particle accelerator, like a SEM, would be unnecessarily bulky, expensive and technically demanding. Without seeing the innards of the sniffer, it's hard to say how compact its XRF unit is. It may, in fact, be a gun. Many of these have a computer interface.

Any stand-alone XRF guns PCGS has are probably used when graders suspect, but aren't certain, that a coin is a counterfeit. If you send a coin to PCGS for elemental analysis, they send it out to a private lab that uses SEM. SEM provides a more accurate elemental analysis. Beyond that, SEM can analyze multiple, very small areas on the coin. An XRF gun is like a shotgun; SEM is like an expensive rifle with a scope.

I suggest Wikipedia for further reading:

https://en.wikipedia.org/wiki/Energy-dispersive_X-ray_spectroscopy

https://en.wikipedia.org/wiki/X-ray_fluorescence

Cal

 

Steve, please consider going to this site https://raregoldcoins.com/blog?category=Articles and read all the articles and blog posts.

 

Thanks, I am familiar with Doug just naturally encountering him during my research. I feel half the PCGS write ups in their registry guide is Doug ha. His knowledge is truly amazing! If I can acquire a fraction of his expertise I’ll be a happy camper.

 

A general answer statement equivalent to your query is that the constituent basis of the epoxy/acrylic/cyanoacrylate/etc. would determine if/what/how "putty" may be removed or altered without harmful effects.

I could design a solventless "process" that would remove the "putty", generally restoring the original state.

JMHO

 

Doug,

You posted the following link:

https://www.pcgs.com/news/pcgs-coin-sniffertrade-uses-advanced-technology-to-detect-doctored-coins

Here's a quote from it:

"The PCGS Coin Sniffer uses dispersive X-ray spectrometry (EDX), Fournier Transform Infra-Red Spectral analysis (FT-IR), Raman Spectroscopy and other analytical techniques to detect the kinds of materials applied by so-called "coin doctors" to conceal problems with a coin or alter its surface to improve its appearance in an attempt to artificially increase the coin's value."

Cal

 

I don't think I've missed your point. I was just correcting a misstatement. Of course, the sniffer can do more than XRF because it incorporates other instruments in addition to XRF. XRF is part of it because some doctoring techniques add new metallic elements to the surface of the coin or may add metallic elements that are already present but in different proportions. A bonus is that some types of counterfeit coins may be detected by the sniffer's XRF component when passing through it.

"Sniffer" appears to be a misnomer. None of the instruments that PCGS has revealed to be part of it test gaseous emissions.

Cal