Coins Altered to Fool the Collector

This is obviously a more critical discussion to the dealer and collector than coins altered to pass in commerce, as it directly affects the value of collectible coins, tokens and medals.

There are a couple of major categories to discuss.  First, there is either the removal of something or the addition of something to the coin, in order to create the appearance of a more valuable date and/or mintmark.  This is most often the removal or addition of a mintmark in order to create a "key date" coin from a more common one.   This has long been a problem with the 1909-S, 1914-D and 1922 "Plain" Lincoln Cents, 1937-D 3 Leg Buffalo Nickel, 1916-D Mercury Dime and 1893-S Morgan Dollar, to name the most commonly altered collector dates.

Second, there is the alteration of a coin's surface to give the impression of a higher grade and therefore higher value of the actual date/mintmark.  This includes cleaning in all of its forms, re-engraving detail, the more modern problems of adding material to a coin to "enhance" or replace lost detail, adding artificial "frost" to simulate a Cameo surface, and many others.

A third and somewhat less critical category are alterations that were done for reasons other than to enhance the "collectibility" of a particular object, but rather to serve a particular non-numismatic purpose or satisfy a whim.  This includes the wide field of altered coins such as hobo nickels , "potty dollars", opium dollars, coins cut out for jewelry, "two headed" coins (usually produced for magicians), love tokens and various gold and/or silver plated coins.