An easily overlooked counterfeit "S" can alter your coin's value by hundreds of dollars. Are you at risk?
As the demand for date and mint coins of a particular series increases, there is an increased incentive to fill the demand with altered coins. Walking Liberty halves have been popular for some time now, especially the "short set" made up of late dates. The price for earlier dates and mints has also increased, possibly due to the desire of some collectors to expand their collection to include coins from the Thirties.
As a result, counterfeiters have a new group of coins to target. The 1938-P half dollar has always been a good candidate for alteration as the Denver Mint coin of that date is a key. Now we are seeing some other coins becoming targets. The Brilliant Uncirculated 1935-S illustrated here was made by adding an "S" mintmark to a 1935-P coin. This alteration gives a nice return for the effort considering that the host coin, a 1935-P, is relatively inexpensive. Checking the Coin Dealer Newsletter, a 35-P in Uncirculated lists from $28 to $50 (MS-61 to MS-64) while a 1935-S goes for $180 to $430 in the same grades. Altering a 1934-P coin in the same way shows even better potential for gain.
The fact that a collector might not be looking for an added mintmark on this date (we cannot remember seeing one before) makes this alteration all the more dangerous. Authenticators can detect the alteration because the shape of the "S" is wrong and the field around the mintmark is disturbed just enough to easily confirm suspicion under magnification.