Question about US Gold coin collecting

The PCGS sniffer is a trade secret. It is known that it uses multiple modalities of analysis (X-ray spectrometry, FT-IR, Raman spectrometry and more). The database and software are also trade secrets. They're not about to share any of it with NGC.

The sniffer is likely used on some coins not submitted for Gold Shield service. If graders suspect a coin has been doctored, but aren't sure, it probably goes through the sniffer.

Cal

 

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I'm sure NGC can do something similar on their own.

 

Yes they can. They just need to spend the money to do it.
Cal

 

Doug,

Nice to know that. Thanks.

Cal

 

Back to the OP, our discussion seems to confirm that starting with the rare dates is not the way to go. As we spend on coins with numismatic value over intrinsic value, we really need to do our homework first.

 

What is used to remove the putty?…Spark

 

Are the specific solvents a TPG trade secret? Acetone is a solvent, so is gasoline, kerosene, xylene, benzene...you get my point. What is normally used?

Thanks for the info...Spark

 

If they sniffed every coin and got a readout that the coin had some kind of chemical residue from lets say cleaning they would know but do they tell you? because there are alot of cleaned coins out there. I am talking about those ray gun things that cost thousands.

 

Most chemicals used in cleaning don't leave behind detectable residue (assuming the coin is properly rinsed and dried after cleaning). It's the physical effects ... lines, abrasions, weird coloration, luster changes, etc. ... that are signs of cleaning.

The "ray gun" is a x-ray fluorescence (XRF) analyzer. XRF analyzes the proportion of metallic elements on the surface of the coin. Therefore, it wouldn't detect most cleaning agents even if they were on the coin. What it can detect is many types of counterfeits, and metal and metallic paints used to alter coins. It's also useful for differentiating some patterns that were made in similar, but different, alloys.

BTW, it does not make the coin radioactive.

Cal

 

Not sure if my last reply stuck because I wasn’t logged in. I’ll repost:

Thanks again everyone for the information. This thread has morphed a bit into different areas and I’ve been sitting back absorbing the knowledge.

I’m certainly paranoid about cleaned or altered coins. Quick question on grading. How do most go about doing it? Send in themselves, at a show, or through a dealer? I would like to have my first half Eagle graded to give me peace of mind. It’s looking like between the membership costs though grading one coin is fairly expensive. Maybe I’ll just suck it up.

 

I've done what you're suggesting, for several reasons, mostly because the coins are generally in a reasonable price range. If you purchase based upon value, you may find, as I, when locating some valuable/beautiful VF condition coins. I love both the Liberty and Indian coin designs, and have beat inflation over my 50+ years of collecting the coin.

I suggest you don't concentrate on grade or TPG, and with patience you'll ultimately be pleased. NOTE: Try not to purchase raw, for multiple reasons, which only collecting will supply understanding.

I have spent decades finding some dates/mints, so learn patience and comparative value.

This post is worth approximately that paid, so start your learning process slowly, then you may live long/wise.

JMHO

 

You can find a reputable dealer to send out a coin for you, most will do it at close to their cost and already have packages going back and forth to PCGS and NGC on a regular basis. But before you get deep into grading expenses, you should learn to get an eye for grading yourself. Talk with other collectors, tape over the grade on a slab and see if you come up with the same grade as the TPG, look at dozens and dozens and dozens of coins.

 

Thank you how much does a xrf gun cost? xrf. Is there a gun that will smell residue like pvc slime

 

Roughly $8000 to $15000

 

Well, not a gun, but sure, there are instruments like IR spectrophotometers (it's part of the PCGS sniffer) and gas chromatography that will detect PVC residue. PCGS caught it with the sniffer on an Arkansas commemorative that I submitted. I didn't have a clue when I submitted it.

Cal

 

thank you