When the U.S. Assay Office was established on Jan.28, 1851, the duties were done by Augustus Humbert, who was a New York watch case maker. A private mint owned by Moffat & Co. immediately offered their services & received a contract the following day Jan 29, 1851, which announced the opening of the U.S.Assay Office. The Office received the authority to strike gold coins in the values of $10 & $20.00 on January 7, 1852 from Secretary Corwin. The reverse has an embossed surface known as “engine turning” (a wed-like pattern that was impossible to duplicate). The obverse has the legend “United States of America” & the value of $10 or $20.00.
CG-4 $20 coin