Ron Guth: The first Kennedy Half Dollars were made of 90% silver, as were all Dimes and Quarter Dollars produced in 1964. In 1965, the silver in the Half Dollars was reduced to 40% silver, while the Dimes and Quarter Dollars were made with outer layers of copper-nickel over an inner layer of pure copper.
The Kennedy Half Dollar was an instant succes and the entire mintage was absorbed by eager collectors and people who wanted souvenirs of this popular president. Many pieces went overseas, where Kennedy was just as popular as he was in the States. Kennedy Half Dollars were available through banking institutions, but few were used in actual commerce, a situation that changed little in subsequent years. Today, the 90% silver versions are prized for their metal value, which fluctuates with the daily price of silver. Thus, many of the 1964 Half Dollars have been melted down over the years, including the Uncirculated versions (which carry little or no premium over circulated examples). Nevertheless, the Kennedy Half Dollar remains very popular with collectors because of its theme and the relatively low cost of building a quality collection.
Beginning in 1992, the Mint offered special, 90% silver Kennedy Half Dollars for sale to collectors; these are available only as Proofs. In 1998 only, 90% silver Half Dollars were issued in both brilliant and matte Proof formats. The later 90% silver Half Dollars are included with the 1964 issues as a distinct type because of their similar metal content.
The only major variety of this sub-type is the "Accented Hair" variety of 1964, which shows much deeper definition of Kennedy's hair. Supposedly, Kennedy's widow, Jacqueline, disapproved of the design, which was later modifed, but not before an unknown quantity of Proof coins had been struck.