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Treated surfaces sticky to touch

What you are about to read is heresy. Sometimes it’s OK to touch the surface of your coins. That’s because, in some cases, the method used by coin doctors to alter a coin’s surface will leave a sticky residue that is easily detected by touch.

What you are about to read is heresy. Sometimes it’s OK to touch the surface of your coins. That’s because, in some cases, the method used by coin doctors to alter a coin’s surface will leave a sticky residue that is easily detected by touch. Nevertheless, if you follow some of the tips I’ll give you in this column, you should be able to spot many surface alterations with your hand lens rather than your finger.


First, let me say that I do not need to touch our customer’s coins in the authentication room because I use a stereo microscope during examinations. It’s a luxury that few collectors have. The microscope along with fluorescent lighting allows me to see if a coin’s surface is original or has been altered either by mechanical means or with some chemical or residue.

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After making this disclaimer, let’s go back to basics. Bag marks, scratches, and other forms of “impact damage” result when something strikes the original surface of a coin. Any marks will detract from a coin’s eye appeal. Eye appeal is extremely important when grading a coin. That is why not quite uncirculated specimens with nice eye appeal are bought, sold and graded by knowledgeable numismatists in the uncirculated price ranges.

Therefore, anything that an unscrupulous individual can do to a coin that raises its eye appeal will raise its grade and value if the alteration goes undetected, or is purposely ignored by the seller. In my experience as a professional grader, I have witnessed both of these cases first hand so it is up to you to become an informed collector. Until you learn what to look for, it’s best to buy coins certified by one of the major grading services. I also recommend taking one of the grading seminars offered around the country. Hopefully, with a competent instructor, you should learn how to detect coins with altered surfaces.

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The first characteristic you should look for as you examine a coin is its originality. An eye for originality can be developed over time by closely examining high grade coins in major grading service slabs or government holders. I recommend collectors purchase a Carson City silver dollar in a sealed government holder to learn the color and appearance of one type of original mint luster seen on many coins. Unfortunately, these coins have been priced out of the budget of many beginning collectors.
Fortunately, there are many pre-1964 silver coins graded MS-65 and higher by the major services that are well within a modest budget. Examining coins minted prior to 1964 is best because the alloys and methods of striking coins at the Mint has changed enough over time that the surfaces of original “vintage” coins differs from original coins made more recently. Once you learn what an original coin looks like, a coin with an altered surface should stand out.

Keep in mind that contact marks to an original surface will change the color of the surface at the point of contact. In most cases, the mark will be shiny and remain that way until the surface becomes oxidized over some period of time. As I examine a coin, I’ll look for contact marks that are dull, having the same tone and color as the surrounding surface. Heavy marks on the cheek of the Morgan dollar in Figure 1 have been subdued by a chemical alteration. Older original coins that are not altered – just toned – often look this way; but you’ll be able to see the difference between an alteration and natural toning as you gain experience.

Some other indications that a coin has been altered can be found at the border where the relief design meets the field. Look for a “reaction ring” where a chemical build-up has dried, forming an outline or a “halo” around stars and letters. In many cases, the substance used as a covering coat will fill up the intricate design details of the portrait and crevices in letters. It can be scraped off gently using a rose thorn. In Figure 2, I have pushed-up a translucent, waxy residue that was coating the surface of a gold coin. Many altered coins such as this, will be sticky when lightly touched on their “frosty” devices. Very often these “sticky” coins will have very tiny fibers and lint adhering to their surfaces that was picked-up from some fabric or flip. Needless to say, avoid touching proof and proof-like fields.

Also look for the “overspray-effect” where the chemical alteration has reached into parts of the field (Figure 3). This is commonly seen on proofs that have been altered to show a cameo contrast.

Keep in mind that two of the coins I have illustrated here are crude attempts at alterations. Others are far more deceptive so have any suspect coins checked at a major grading service.

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