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Chemical residues hard to detect

I’ve probably been boring readers writing about coins with altered surfaces; but it is still a big problem. I see the evidence of this at every coin show I attend and with many of the coins submitted to ICG for crossover service or upgrade.

I’ve probably been boring readers writing about coins with altered surfaces; but it is still a big problem. I see the evidence of this at every coin show I attend and with many of the coins submitted to ICG for crossover service or upgrade. The Professional Numismatists Guild along with other major grading services have made it clear that they will not tolerate surface alterations and have spent time and money to develop new technology to “sniff out” these coins. It will not be easy. It has been a while since a discussion of this subject took place in this publication. I’m still waiting for the PNG to publish a definition for “coin doctoring” or what constitutes an unacceptable coin with an altered surface. The real challenge will be to actually detect the alterations.


In a previous column, readers may recall that I discussed the “learning curve” that any new authentication and grading firm needed to go through before it reached an acceptable point. After almost 15 years in the business, we had a good laugh at the repaired, buffed and altered coins we saw in the “newcomer” slabs of the mid-1980s.

This learning curve is similar for any new dealer or collector. There will be mistakes made along the way. Coins will be sold too cheaply or bought overpriced. Counterfeits will be bought or traded. It is a natural progression that one must go through to gain experience. Fortunately, collectors of today start out with a giant leap from those of us in the past due to the information and seminars available today. Now, the major grading services have been in existence for a minimum of 20 years. They have hired or trained top professionals in their field; yet, there is still a problem with altered coins being certified in slabs.

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I believe there are two reasons for this. Often an alteration is missed or judged to be “market acceptable.”
Perhaps, a hint of unnatural color over some marks on the cheek of a Morgan dollar may result in a slight downgrade rather than a “No Grade” decision. Face it, it’s a sure bet that something has been done to a majority of coins over the years. They may have been mishandled, cleaned, dipped and toned. Grading services are aware of this and cannot be too critical.
Another, and perhaps the principal reason an altered coin may be certified is that its surface changed after it was graded. Let me illustrate this with an example that has nothing to do with alterations. I worked at PCI grading service in the early 1990s. One innovation we did to help collectors purchase our coins sight-unseen was to note the percentage of “whiteness” on a silver coin. Thus, a brand-new 1994 silver Eagle would be graded 100 percent white. Unfortunately, over a period of time after they were slabbed, many of these coins began to tone; much like what happened to the Redfield dollars. Many PCI Eagles toned completely with unusual colors such that if ever removed from their slab, most would be rejected by professional graders as “Questionable Toning.”

The point I am making is this: Coins are at some grading services for a very short period of time. Many have been dipped previously and not neutralized properly. This leaves a chemical residue that will be unseen until it turns color in the slab much later. Some coins fresh from the Mint will develop spots over time. Even the moisture contamination that may be present in the air hose used to blow out the plastic slab parts and the coin may cause problems at a later date that will drop the grade from that originally assigned on the label. These are all natural things that cannot be helped unless each coin is conserved before it is slabbed (A recommendation I made at each of the five grading services where I’ve worked).

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The most insidious forms of surface alterations and the one’s that the PNG and major grading services are combating are the laser and chemical alterations done by the “professional coin doctors” who have been plying their trade for years. Some are experienced chemists. At a weak moment many will brag about what they have slipped past the grading services.

Perhaps, with new technology it will be harder for them to survive. Nevertheless, coins they have worked on in the past are still in slabs. I encounter them almost on a weekly basis.

Let me show you one characteristic to look for to avoid many of these coins. The example shown here is easy to detect especially using fluorescent light. With the slab tilted at 45 degrees, two different colors can be seen on the surface of this $20 coin. The micrographs appear fuzzy due to the plastic slab. The lighter color that spreads onto the field indicates the area that was chemically altered. The coating mimics the natural “skin” that is so desirable on original coins. Apparently, this chemical turns into a slightly “bluish” haze at some point after it is graded. These coins will eventually be removed from the market. For now, be careful what you buy.

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