Little is known about the San Francisco Standard Mint. It was certainly a private venture with no connection to the federally sponsored United States Assay Office of Gold or the later San Francisco Mint. Some numismatic scholars believe that the dies and the coins that they struck were made in the East by some person or entity that hoped to engage in coinage upon their relocation to the West Coast. Others, Donald H. Kagin and John J. Ford, Jr. among them, believed that these die trials were made in Birmingham, England in 1851 by an English company as a proposed general coinage for Gold Rush California. Proponents of that theory suggest that the initials W.J.T. on the base of Liberty's portrait represent the British engraver William J. Taylor. In either case, the San Francisco Standard Mint die trials are notable rarities that seldom appear on the market at any level of preservation.