unnaturally treated to hide hairlines and imperfections.
Reprinted with permission from Professional Coin Grading Service (PCGS). Excerpt taken from The Official Guide to Coin Grading and Counterfeit Detection
For a look at chemically altered and toned coins, click on Detecting Doctored Coins, Part One.
DETECTING SOPHISTICATED SURFACE ALTERATION TECHNIQUES
There are other ways to hide or obscure surface problems besides adding color or toning. The most common of these surface techniques is the application of "nose" grease. This combination of skin oils and other skin chemicals often is used to dull shiny spots on the high points of coins that may represent slight wear or incomplete striking. Sometimes this method also is used on tiny marks or light hairlines in the fields, thought it is usually easier to detect in the open fields than on high points.
When the amount of nose grease used is minimal, this type of alteration may be difficult to detect, since the area doctored may be essentially clear and quite small. When larger amounts are used, the surfaces sometimes have a golden or light yellow-brown color and may be slightly opaque. Over time, most of the coins "done" by this method will start to discolor, the treated area becoming brown and splotchy. This technique is used on gold, silver, nickel, and copper coins, but it usually is more obvious on silver coins. "Thumbing" and Other Techniques
One common variation of nose grease is a process called thumbing, which is used mainly on silver dollars. In this process, the skin oils are rubbed across the desired area, with the thumb acting like a brush, rubbing the oils into the "skin" of the coin. This method is often used to obscure shiny lines or marks on the face of Miss Liberty on Morgan and Peace dollars, and is sometimes so minor that it is nearly undetectable. The breast feathers on Morgan dollars are sometimes "dulled" by this method also, especially when there is a shiny area resulting from contact. When the oils are applied vigorously, the affected areas appear duller, with the luster inhibited. When the coin is tilted under a good light source, the marks or hairlines that have been obscured by the thumbing are visible-though some "thumb" experts are so skillful at this technique that their handiwork is difficult to detect. Once you become familiar with this method, you will usually have no trouble recognizing the telltale signs-principally the dullness associated with the thumbed area.
Dental wax and auto-body putty also are used for surface alteration. Dental wax is particularly subtle because it leaves a thin, clear layer on the area where it is applied. This substance is used much like nose grease. Nothing is contained in the wax to discolor a coin's surfaces, but sometimes, after the water and alcohol have evaporated, a white powdery residue can be seen.
Auto-body putty and other car products were first used on Morgan dollars to duplicate frosty devices or cover blemishes on Miss Liberty's face or the eagle's breast feathers. PCGS has seen this method used on three-cent nickels, where the head of Miss Liberty was "frosted" with these compounds. This is not considered a very deceptive method because it is easy to spot after having examined a few of the coins on which it was previously used. This is also considered a form of artificial frosting, therefore could have been listed in the next section on chemical etching and artificial frosting. It is listed here, however, because it is more a method of surface alteration than a chemical process.
Although it is used only occasionally, whizzing should be mentioned here, since light whizzing plus added toning can be deceptive. Whizzing is a technique in which surface metal is moved mechanically to create the illusion of luster. Heavy whizzing produces unnatural surfaces whose brightness does not resemble original luster. The "cartwheel" effect is replaced by a "sheen" that causes light to bounce off the surface differently, often with a diffused effect. When whizzing is light and is covered by natural or artificial toning, it is much more difficult to detect. If a coin lacks sharp detail but the luster appears full, light whizzing may be the culprit.
Magnification is the best way to differentiate weakly struck coins from worn-die and lightly whizzed coins. On weakly struck coins, flow lines will still be present and luster will still "cartwheel." Worn-die coins may not have much "cartwheel" but still may have radial flow lines often the result of die erosion. Whizzed coins will appear smooth, and because the flow lines have been disturbed, they will not have normal "cartwheel" luster, but rather a diffused look.
A sophisticated whizzing process is sometimes used on Proof coins, though PCGS has seen it on a few proof-like business strikes as well. This is a refinement of the process used to create the so-called "California Proof" Morgan and Peace dollars. The most common method involves the use of a high-speed drill, such as a dentist's drill, with some type of fine burr or attachment to "enhance" the surface and smooth away scratches, marks, and hairlines. Recently, PCGS has seen some very deceptive coins, mostly Proofs, with plated-looking surfaces, possibly produced by this method in combination with chemicals and/or heat. The plated appearance hides hairlines, planchet flaws, marks, and other defects. These surfaces have a "chromed" look that, once noticed, will appear very unnatural.
In yet another form of surface alteration, the surfaces of Proof coins are heated to actually melt the hairlines or other defects. This method may involve anything from a match held under the surface for a few seconds to a high temperature torch selectively applied to a specific area. Coins altered in this manner sometimes have a wavy look or different "depth" to the mirrored surface. These clues are especially noticeable on Proof gold coins, since the surfaces are so delicate. Also, many Proof gold coins have "orange-peel" surfaces that are flattened by this method. If the mirrored fields vary across the surface of a coin, heat treatment of the fields is often the cause.
CHEMICAL ETCHING AND ARTIFICIAL FROSTING
To create the cameo devices seen on many U.S. coins, the Mint sometimes sandblasted the dies or pickled them in acid, then polished the fields, leaving the recesses of the dies with rough surfaces that produced the frosty devices. Before the introduction of completely hubbed dies, the die-making process also contributed to frosted letters and devices, because the ends of the punches were not always smooth. This roughness, and the pressure used to impart the letters and devices to the dies, often left the recessed areas with "frost." This resulted in frosty letters or devices from the letter- and device-punching process. Proof coins almost always were struck from these specially prepared dies, and some business-strike coins also were struck from the Proof dies and other dies treated in a similar way.
To recreate this frost, some coins are chemically treated on the devices, often with mild acids. PCGS also has seen some other coins, usually Proofs, which appear to have had their devices lightly sandblasted or acid-etched to imitate frosting. Other substances also are used to imitate frosting-among them auto-body putty, as mentioned in the previous section-but these will usually "dip off' in commercial dips or certain organic solvents. These treatments are applied most commonly to silver coins, but gold, nickel, and even copper coins also are sometimes seen with imitation frosted devices.
LEARNING TO DETECT DOCTORED COINS
Examining coins known to have been doctored in particular ways is the best way to learn how to recognize the various processes used and their results. Seeing such coins is worth even more than the "thousand words" of the old saying. No amount of discussion or analysis can fully instruct one about the subtle differences between original and altered coins. With experience, one will be able to spot certain doctored coins with just a casual glance. Once a particular process has been "seen," coins that result from that process may very well become extremely obvious.
Some of the alteration techniques are difficult to detect, and even experienced numismatists miss them at times. As more and more coins are examined and the "look" of totally original coins becomes increasingly familiar, any deviation from that look will serve as a tip-off to coins that have been altered in some way.
A coin is not necessarily ungradable just because it is not totally original. In some cases, in fact, altering a coin may actually improve its grade. One example of this would be dipping a coin that has splotchy, mottled, or dull toning and thereby revealing a blazing white gem. Another would be removing PVC flip damage with an organic solvent. Also, with gold, silver, and nickel coins, rinsing them in hot water sometimes is necessary to remove light surface contaminants. This should not be employed on copper coins, as the chemicals in the water plus the heat may affect the color and luster. Copper coins are much more difficult to work with, and in most cases should be left alone. If green corrosion appears on the surface of a copper coin, remove it mechanically, if possible, usually with a soft camel-hair brush. Copper aficionados sometimes have brushes they have used for decades, carefully protecting them. These "used" brushes have oils from years of use and their owners swear that these "protect" the surfaces of copper coins brushed by them. There is truth to this, as many coins brushed appear unchanged after many years. These, however, should only be used by knowledgeable copper experts, because even the fine camel hair can damage surfaces. Only when this method has been tried and failed should one attempt to remove something chemically from the surface of a copper coin.
Obviously, one needs to learn what is acceptable alteration in order to know what is not acceptable. Once the original and non-original "looks" of coinage have been mastered, one must learn what is acceptable and not acceptable for coins that are not original. When unsure about a coin, ask the owner. Although the owner wants to sell you the coin, he or she does not want you to call six months later and ask why the coin has changed colors.
There are many subtle areas that only experience can clarify. The cloudiness on shipments of U.S. gold coins imported from Europe is very similar to the hazing or "smoking" seen on some altered coins. Second toning, in many cases, looks similar to artificial toning. The difference is subtle, but there are telltale signs that knowledgeable numismatists recognize. Learning the difference takes time and effort, but an "eye" can be developed for the "look."
For a look at chemically altered and toned coins, click on Detecting Doctored Coins, Part One.
Artificially frosted. This coin was chemically altered to simulate the frosted cameo effect found on the devices and lettering of many Proof issues. Note lines and marks under the frost.