Frederick Kohler opened the State Assay Office at San Francisco on May 13th, 1850. Six ingots have been reported from the San Francisco State Assay office; however, only four of these have been seen in recent memory (Kagin-1, Kagin-3, Kagin-4, and Kagin-5). Presumably, the other two examples no longer exist. Each ingot is unique, bearing the State Assay Offices stamp, the year of manufacture (all are 1850), fineness expressed in carats, weight expressed in pennyweights, and value. Of particular interest is the $50 Kagin-5, which is the earliest $50 piece in the U.S. series.
| Country | United States of America |
| Year | 1850 |
| Serie | F.D. Kohler |
| Denomination | G$45.34 |
| Mint | San Francisco |