Coming off the back of the Professional Numismatist Guild's (PNG) recent efforts to reduce the quantity of counterfeit coins offered for sale via eBay, PNG has just published a revised definition of a (draft) policy they are seeking to have their members abide by.
Although the PNG does not presently have any members in Australia, it remains the peak body representing professional numismatists around the world - the actions taken by this organisation reverberate around the world, Australia included. It's membership is primarily US-based, and in my opinion, the drive for a definition of the term "coin doctoring" is a function of this - "coin doctoring" is a practice that is far more relevant in the US than it is in Europe, and certainly more prevalent than it is in Australia.
That said, I believe the PNG should be applauded for the leadership it is showing on this issue - it is all good and well for collectors and dealers to complain about a particular problem that the hobby and or industry faces, it is quite another thing to take action that seeks to reduce it.
If you think you're not clear on what the definition of "coin doctoring" might be, let's just say that it covers any efforts that seek to deceptively alter a coin such that it appears to have a higher grade or value. There are a number of ways that less-than scrupulous dealers or collectors might set out to do this, the exact list of which is the subject of the PNG's current discussions.
You can find an up-to-date draft of the PNG's definition via this link, however here is a summary of a few of the tasks that a "coin doctor" might undertake:
Deceptive surface manipulations are carried out with the intention of altering the appearance of the subject coin, such that it may look to be of a higher grade than it truly is; may garner a higher grade after certification; may gain the attributes of a grade designation that it would not otherwise deserve; or may appear subjectively more attractive. These surface manipulations may irreversibly change the surface of the subject coin and/or may harm the surfaces of the subject coin over time.
Methods of deceptive surface manipulation that are not considered acceptable by the PNG:
1) Mechanical disruption of surface metal (including, but not limited to, puncture or cut surfaces; plug or otherwise repair surface marks or damage; polish, whizzing or laser of surfaces).
2) Physical alteration of design details (including, but not limited to, modification of date or mintmark; engraving of missing or weak details to earn a grade designation; engraving of design details to simulate less wear; other methods to gain grade designation).
3) Application of exogenous materials to increase apparent mint luster, infer less wear, reduce evidence of prior manipulations or cleanings, replace missing details or earn a grade designation (including, but not limited to, application of solder; introduction of glue, plastic or other bonding agents; application of waxes, putties, powders or assorted grease or gels; exposure to dulling agents; addition of PVC; exposure to smoke or other gases).
4) Abrasive cleaning such as, but not limited to, the use of erasers or cleaning pads.
5) Copper/bronze coins are made from the most reactive of coinage metals. They are far more vulnerable to the production of artificial color, typically resulting in, but not limited to, various hues of red, blue and purple. Some conservation techniques safe for coinage produced in nickel, silver and gold consistently produce unacceptable results on copper/bronze. Artificial color may be achieved by exposure to agents that may or may not be acceptable for use on other coinage metals (including, but not limited to, arsenic; thiourea-based compounds; dilute acids; ammonia; chlorine and caustic solutions).
6) Artificial toning is the intentional, and/or inappropriate, accelerated acquisition of surface patina, primarily used to mask impairments on surfaces and/or to increase subjective eye appeal and/or grade. Artificial toning is always prohibited, and may result from intentional or inappropriate exposure to various substances or effects (including, but not limited to, direct heat; electrical current; immersion in certain liquids including bleach and/or others; exposure to gases; intentional or inappropriate storage conditions). It may be facilitated through the introduction of various compounds or catalysts including, but not limited to, sulfur, antimony, phosphorous, iodine, various alkanes, caustic compounds and acids.
Anyone that has a reasonable degree of experience in the Australian numismatic market will be able to recount experience of seeing several examples of each of the "deceptive surface manipulation" techniques listed above. I can think of the following examples:
1) Mechanical disruption of surface metal - it isn't unusual to see Australian gold coins at auction that have had deep scratches, scrapes or gouges rubbed (sometimes professionally) in order to reduce the appearance of the scratch, or try and make it disappear!
2) Physical alteration of design details - I'm not familiar with coins that have been "tooled" to the degree that they reach a higher grade, however there are of course numerous instances where buyers have been deceived by sellers that have altered the date of a common date copper coin such that it looks like a key date coin - a 1923 halfpenny or a 1930 penny for example.
3) Application of exogenous materials - I know that the coin doctors in the US have far more expertise at altering their coins using methods like adding powders, greases and glues than I've seen in Australia. I don't believe there is a significant risk of this kind of coin doctoring going on in Australia.
4) Abrasive cleaning - such cleaning is generally performed by uninformed and overly-enthusiastic owners rather than deceptive coin doctors.
6) Artificial toning - there are instances of artificial toning being applied to copper coins, however as such coins generally have an unnatural colour to them, they are reasonably easily spotted by experienced collectors.
It will be interesting to see what the final definition of the term "coin doctoring" that is adopted by the PNG - I'll keep you up to date with their progress.