Augustus Humbert, a New York watchcase maker, was appointed United States assayer, and he placed his name and the government stamp on the ingots of gold issued by Moffat & Co. The assay office, a provisional government mint, was a temporary expedient to accommodate the Californians until the establishment of a permanent branch mint.
The fifty-dollar gold piece was accepted by most banks and merchants as legal tender on a par with standard U.S. gold coins and was known variously as a slug, quintuple eagle, or five-eagle piece. It was officially termed an ingot.
In 1851, certain issues of the Miners’ Bank, Baldwin, Pacific Company, and others were discredited by newspaper accounts stating they were of reduced gold value. This provided an enhanced opportunity for Moffat and the U.S. Assay Office of Gold. Fractional-currency coins of almost every nation were being pressed into service by the Californians, but the supply was too small to help to any extent. Moffat & Co. proceeded in January 1852 to issue a new ten-dollar gold piece bearing the stamp MOFFAT & CO.