Q. David Bowers (derived from the PCGS Coin Guide): Coronet or Liberty Head quarter eagles, minted nonstop from 1840 through 1907, are remarkable in American coinage as having the longest continuous production of any design without a major change. In essence, a Coronet quarter eagle of 1840 looks just like one of 1907, except for the date numerals. There were several rarities produced within that span, notably the 1841 (believed to have been made only with Proof finish), the 1863 (struck only in Proof finish, to the extent of just 30 coins), the seldom-seen 1854-S (of which just 246 business strikes were made), and the low-mintage 1875.
Particularly notable in the quarter eagle series is the 1848 CAL. quarter eagle, of which 1,389 were produced using gold bullion brought to the Philadelphia Mint from California, one of the earliest shipments to the East from the Gold Rush. The distinguishing counterstamp, made at the Mint while the coins were still in the die, served to hallmark the issue and at the same time to specifically create a souvenir for those desiring same. In actuality, the 1848 CAL. quarter eagle is the first official United States commemorative coin, although few people recognize it as such. Probably somewhere between 200 and 300 specimens survive today.