Q. David Bowers (derived from the PCGS Coin Guide): Half eagles or $5 pieces, a denomination produced intermittently from 1795 to 1929, include some of the greatest rarities in American coinage. Particularly famous is the 1822 $5, of which just three are known, two of them being in the National Collection at the Smithsonian Institution. The third, the Eliasberg coin, was auctioned by my firm in 1982 for $687,500, the same price realized by the unique 1870-S $3. At the other end of the spectrum, numerous half eagles of the late 19th and early 20th centuries were produced by the millions and were used in quantity for large international transactions and are very common today.
In general, half eagle designs follow those of contemporary quarter eagles. There are, however, numerous differences, one of them being the first half eagle design, with Capped Bust to Right obverse and Small Eagle reverse, which has no equivalent in the quarter eagle series, but which is similar to that used on the contemporary $10 piece. $5 pieces of the Small Eagle reverse type were minted through 1798. Those dated 1798 are extreme rarities, and fewer than a dozen are known to exist.
Capped Bust to Right half eagles with Heraldic Eagle reverse were minted with dates from 1795 through 1807, although it is believed that those struck with dates prior to 1798 were produced in 1798 by using obverse dies on hand from earlier years.