Do NGC or PCGS ever use XRF machines for coin authentication?

Does anyone happen to know if NGC or PCGS ever use an XRF machine to determine whether a coin is authentic by looking at the metal content?

I have seen coin dealers do it before. My local dealer has some fake Peace Dollars someone brought in and when he put it on the XRF machine it said that it was silver plated and to investigate further.

Or like for ancient coins if a denarius of Augustus came up as 75% silver 25% copper it would prove it’s fake (or at best an ancient forgery) since denarii of Augustus are always 95% pure or higher (sometimes up to 98%) and didn’t drop to 75% until after Marcus Aurelius which was almost 200 years later.

I imagine if TPGs use scales to check the weight as part of the authentication process they might use XRF machines as well but I don’t know for sure.

They also seem to have the resources to invest in an XRF machine (or a few of them) especially considering they guarantee their coins so letting a fake slip by could cost them big money.

Anyone else know?

 

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@Insider

 

They probably have handheld XRFs. The one time metal composition became an issue with a PCGS coin of mine, they sent it out to an independent lab who used scanning EM. Turned-out PCGS had labeled the coin wrong. There was no real change in value. They relabeled it for free and didn't charge me for the analysis either.

Cal

 

May I ask what coin it was and what was going on?

 

It was a pattern in the goloid series. Many patterns were struck in multiple metals with the same dies ... sometimes more than six alloys. Many of the silver and copper alloys can't be distinguished by eye. However, when these patterns were first submitted as raw coins for TPG grading, the grading services took the word of the submitter as to which alloy it was. In many cases, the submitter had it wrong, and the error was carried forward for decades. Many of the pattern alloy designations on slabs today are questionable. Some auction houses, like Heritage, will sometimes note that a pattern that's up for auction is of uncertain metal composition.

The whole story of my coin is pretty long and complex. I may write an article on it someday.

Cal

 

After I left NGC, they bought some type of spectrometer. I doubt it is a cheap $$$$ hand-held version. I don't know where they would have room for it as the staff has increased by several hundred since I worked there. There was barely any place to park when I was there two weeks ago.

 

I believe NCG did/does offer this as a service...

https://www.ngccoin.com/news/article/1591/

 

Both NGC and PCGS offer metal analysis. I don't know the price, but am pretty sure it ain't cheap.

Cal

 

My guess is that they wouldn't use this type of equipment on all coins.

 

With all of todays technology I believe they would have the best of the best, in my opinion. Great question, thanks.

 

For PCGS, XRF Analysis is performed as part of the Secure Plus Tier of Service, and also when they have a question about the metal composition authenticity of a submitted coin. Likewise, NGC will use XRF when they have a question of a coins metallurgical composition, but they also have an option for the submitter to request a Metallurgical Analysis @ $75 per coin for the following types: "Upon request, NGC performs a composition surface scan. Only coins with non-standard metal composition will have the weight and the three most abundant non-trace metals listed on the certification label. Metallurgic analysis is available for all pattern, essai, trial and mint error coins, tokens and medals."

 

There's a Jewelry store/Gold buyer shop around the corner from me who has an XRF gun. Whenever I buy a coin that could be questionable, I take it there once I receive it, and he shoots it for me for free. It takes just a few seconds and gives a full analysis of the coin's content. I usually test every French Indo China Piastre that I buy. I've only had one that tested bad. It was only 75% silver. I sent it back to the seller and got a refund.

A year or so ago, I disagreed with several CT members who insisted that an XRF gun could only analyze the surface of the coin. Actually the gun analyzes the full amount of the coin that falls within the 'beam' sent out by the gun. After all, it's an XRAY type of device.

 

Actually, a handheld XRF analyzer pretty much is a surface analyzer. Analysis maybe goes down 100 microns, probably less. Problem isn’t the energy of the x-rays shot into the sample by the gun. It’s the lower energy and intensity of the fluorescent x-rays coming back out of the metal atoms. Many of these are absorbed by the metal before they can get to the surface and radiate to the gun’s detector. Past a certain distance, they effectively don't make it out, but are absorbed so much that only an inconsequential number escape. The energy and quantity of these x-rays is what the gun has to capture and analyze in order to determine metallic composition. Much bigger and very costly industrial/laboratory XRF analyzers can analyze down to a few mm.

There are a couple of links below that explain in more detail.

Cal

https://www.researchgate.net/post/I...ration-depth-is-for-X-ray-florescence-in-gold

https://www.horiba.com/en_en/capabilities-of-xrf/

 

They might not understand the technology, and it is not easy to understand off the cuff. It is fluorescent light that is scanned, not different than the gas in a flourescent bulb. It can penetrate the entire coin. It depends on the device, not the technology.

https://www.nature.com/articles/s42003-020-01467-2

https://www.horiba.com/gbr/technolo...ayfluorescence-ed-xrf/measurement-system-xrf/

 

With all of today's technology, the best of the best would cost many, many times a TPG's annual income, never mind profit.

 

I have no idea what there profits are, but the machine itself is cheap to use and quick once it is purchased. It takes more time to "guess" and pick out varieties, and that is manpower hours.

 

It's a good idea to read articles before posting links to them. The first one is completely irrelevant to XRF, and the second is a general high-level summary.

Google can find results for you, but it can't understand them for you.

 

The Advanced Photon Source (which I linked above) is a billion-dollar facility.

 

[strikeout]The first one is COMPLETELY about XRF, being used on fossils.[/strikeout]

Correction - they used Laser Flourecence. Same basic technology.

The second is a run down on the advanced tech, using xrays.