In 1856 Henry Hentsch opened up a banking office in San Francisco. He was twenty-one years old at the time. The local newspaper, the Alta California, ran the following notice on February 2, 1856: "ASSAY OFFICE OF HENRY HENTSCH. Northwest corner of Montgomery and Jackson Streets. I have this day annexed to my Banking Establishment an Assay Office, and am prepared to carry on this business in all its branches.

All orders confided to my care will be executed with promptness, and I will guarantee all my assays. H. Hentsch. San Francisco, February 1st, 1856." Hentsch then listed several international references including prominent European banking firms. Since European banks were a primary destination of California gold ingots and bars, international endorsements attracted depositors with these customers in mind.

A large number of Hentsch bars were aboard the ill fated S.S. Central America to be shipped from New York City to Europe. In January 1863, Hentsch and Francis Berton established a bank and assay business with most of its business consisting of overseas banks and gold dealers.

Hentsch was Consul to Switzerland during this time. The assay business continued until 1873, when it became a part of the Swiss-American Bank. Hentsch moved to Switzerland in 1873 and was made in charge of the bank’s Geneva office. Berton stayed in San Francisco and managed the bank’s office there.