Plain and simple, the 1964 Special Strike Kennedy Half's are not suppose to exist. However, there are about a dozen or so examples which have surfaced in the past 15 years. Therefore, it is the scarcest non error or variety Kennedy Half Dollar in existence.
The 1964 Special Strike Kennedy Half dollars display very unique characteristics unseen on any other coins of the era. First of all, the strike is very sharp as it displays very clear details on both the obverse and the reverse. The coins also contain a smooth satin like appearance with the rims being very square and sharp. There are die polishing lines throughout the coins surfaces. These coins also tend to lack contact marks unlike business strike coins, indicating that they were struck and handled under extreme care. Furthermore, the coins do not display the reflective surfaces that are usually encountered on proof coins.
These 1964 Special Strike Kennedy Half’s were first noticed in 1993 when they appeared in a Stacks auction. Apparently, the coins originated from Lester Merkin who was a well known coin dealer. His collection was later consigned to Stacks. It is also believed that Lester Merkin initially acquired the coins from a Mint employee or Eva Adams who was former Director of the U.S. Mint.
Coincidentally, there are also other Special Strike coins in different denominations that exist for this date. These include the Lincoln cent, Jefferson nickel, Roosevelt dime and the Washington quarter. There is also about one or two dozen sets believed to exist for each of these denominations.
In numismatics there are also other coins which are not supposed to exist, such as the 1933 Saint Gaudens double eagles and the 1913 Liberty nickels. It also took years before some of these coins ever surfaced, and the entire circumstances in how they eluded the U.S Mint is also a complete mystery. Although, the 1964 Special Strike coins are not necessarily in the same league as other classic rarities, they do tend to have the same mysterious history behind them. The fact there are also very little examples of these coins in existence and much cheaper than other legendary coins, only makes them much more desirable to a lot of collectors.
As of September 2009, PCGS has only certified 12 examples of the 1964 Special Strike Kennedy Half Dollars in all grades combined. In conclusion, this also makes it the scarcest of all the 1964 Special Strike coin denominations produced.
One of the interesting diagnostic features of the Specimen Strike 1964 Half Dollars is a small, raised defect that appears to hang from the crosslet of the 4. This defect has been seen on all examples except one. In an admittedly rare hypothtical situation where one of these remarkable coins was spent, the defect can be used to confirm the original status of the coin.