A curious feature of the Kennedy half dollar series is that only the first year of issue, 1964, was available in Proof format before an immediate change.
From 1965 through 1967, the primary period of transition from silver to copper-nickel clad coinage, no Proof coins were issued by the U.S. Mint. Instead, the Mint sold Special Mint sets, abbreviated “SMS,” a hybrid of the annual Proof and Uncirculated Mint sets they replaced.
Cased in plastic and offered as five-coin denomination sets, SMS coins were struck from polished dies but lack the typical sharpness and depth of mirror of true Proof coins. Several important Kennedy half dollars are from these offerings.
First, any 1965 through 1967 SMS Kennedy half dollar that has an Ultra Cameo or Deep Cameo finish is highly coveted. Cameo contrast coins, struck from fresh dies and exhibiting strong contrast between the fields and design elements, were randomly included in a small number of Special Mint sets. High-grade Ultra Cameo examples can be worth thousands of dollars today and are among the most valuable of all Kennedy half dollars.
The 1966 SMS half dollar can be found without the designer’s initials, FG for Frank Gasparro, on the reverse of the coin. The 1966 SMS No FG half dollar continues to grow in popularity and value. Only several hundred are known. Although no formal explanation exists for its omission, likely overpolishing of a later state die effaced this detail. The coin is unknown with cameo contrast, which supports this late die state hypothesis.
The No FG variety has been repeated on several circulation issues; most commonly collected are the 1972-D No FG and 1982-P No FG half dollars, although other dates have been reported and are sought by specialists. The SMS version is the most desirable.
Maybe the most valuable of all Kennedy half dollars, and a great curiosity among modern issues, is the so-called Special Mint set 1964 Kennedy half dollar. In 1993, a group of Specimen 1964 coins were offered in a Stack’s auction. These coins were very sharply struck, like Proof coins, from polished dies. Although their finish was satin rather than brilliant, they were likened to the 1965 through 1967 SMS coins.
Some speculated that these were from the estate of former Mint Director Eva Adams. They were thought to be either prototypes of the SMS finish or simply special souvenirs of the last 90 percent silver coinage. The sets have been broken up, and coins are available singly.
Fewer than two dozen Specimen 1964 Kennedy half dollars are known. The last example to sell at auction crossed the block in 2010 — a Specimen 67 graded example, realizing $16,100!