Q. David Bowers (derived from the PCGS Coin Guide): Following the discovery of vast quantities of gold in California, the Treasury Department decided to create a new denomination called the double eagle, for it was twice the size of the previous highest denomination, the eagle. First minted for circulation in 1850, production of $20 pieces was continued through the year 1933. Vast quantities were minted of certain dates, as they served as a convenient way to convert gold bullion into coinage form. Double eagles facilitated international transactions of large value in an era in which foreign governments and commercial interests were wary of accepting paper money.
Double eagles of the 1850-1907 years are of the Liberty Head type and are the work of James B. Longacre, who produced many other designs of the mid-19th century. There are actually three varieties of Liberty Head double eagles: the 1850-1866 style with the denomination expressed as TWENTY D, the 1866-1876 style with the denomination expressed the same way but with the addition of IN GOD WE TRUST, and the 1877-1907 type with the denomination expressed as TWENTY DOLLARS.
Among double eagles of the 1850-1907 era, there are a number of scarce and rare issues, notably the 1854-O, 1856-O, 1861-S Paquet reverse, 1870-CC (a particularly elusive variety), and the 1879-O. Among Philadelphia Mint coins, the 1883 and 1884 were minted only in Proof finish, with no related business strikes, to the extent of just 92 and 71 pieces respectively. Several other issues are elusive, and the Philadelphia Mint version of the 1861 Paquet reverse is a landmark rarity.
Notice must be paid to the 1857-S double eagle, not a rare issue, as 970,500 were minted, but a piece which is not particularly easy to find in Uncirculated grade (nor is any other double eagle of the 1850-1866 type plentiful in Mint State). In 1989 the numismatic fraternity - indeed the entire world, consisting of numismatists and everyone else - was surprised and delighted by the news that a team of skilled scientists had discovered the wreck of the S.S. Central America, which had sunk in a hurricane off the coast of North Carolina in September 1857, with the loss of several hundred lives, one of the greatest disasters of the era, a tragedy which, somehow, had largely been forgotten in popular literature since that time.
Using sophisticated recovery techniques, employing a robot device and a special chemical preservative compound to surround the artifacts discovered, the team brought to the surface a vast treasure of numismatic items, including thousands of 1857-S double eagles in pristine condition, which had been part of a shipment from the San Francisco Mint to the New York Assay Office.