The obverse being modeled after the beloved president that was gunned down in the prime of his life. Americans see this icon related numismatic object as a collectible as well as in their pocket change.
Minted in 900 fine silver for the entire year of 1964, many have no idea that 1965 through 1970 half dollar issues also contain silver. The amount of silver was reduced in 1965 to keep the value of the coin closer to the silver content's value. An item from these years will be made of 40% silver and contains .1479 ounces of the precious metal.
Composition of the coin was again changed in 1971 to a clad planchet with no silver content. The price of silver had risen to be more then the face value and therefore the metal connection to value was abandoned.
Gilroy Roberts was the designer of the obverse and also was employed as the chief engraver for the US mint. He has the recognition to prove it as his initials grace the front of the issue, just below Kennedy's bust.
Special collector mint sets were made with these coins included, in 1965, 66, and 1967 and they were made in both clad issues and a silver set for collectors. These also carry a premium, because no proofs were issued for these years.
In 1995, the mint at West Point struck a matte version of this coin to be included in a two coin set, which had the half dollar, as well as the one dollar coin, depicting President Kennedy's brother Robert.
The Robert Kennedy dollar and John F Kennedy matte proof half dollar made up a collector set and was sold directly to the public by the US mint.
Only 50,000 of these sets were produced which causes only 50,000 full sets of Kennedy halves to be possible. There are many times that many collectors of this popular American half dollar. Unfortunately, most of them will never complete their sets.
Double dies exist for several years and error coin collectors avidly seek these items out. They hold a greater value then a normal strike as they are all rare.
By the time these were minted, the United States mint quality control had come a long way. Most error coins were found by the mint and removed, prior to making it into circulation. Some, however, slip through and these are the reason the error coin collector base exists.
United States Kennedy Half Dollars have always been one of the United States' proudest numismatic items and new collectors enter the market every day. Prices realized have jumped dramatically recently, most likely due to the arrival of eBay and other auction sites on line.