Frederick D. Kohler was a jeweler and alderman in New York City. He and David C. Broderick formed a partnership in San Francisco in 1849 operating an assay business called F. D. Kohler & Company. Both men had also been firemen in New York City. In San Francisco they were also in fire protection. Kohler was the first chief engineer of the Empire Company, and Broderick was the foreman. Later Broderick became a politician and was elected senator.

In 1848 gold had a value of $18.00 per ounce. California gold varied from $17.90 to $18.20 per ounce depending on the location of the source. However, miners were getting only $16.00 per ounce. If quicksilver or amalgam was used to extract the gold, it would bring $14.00 per ounce. Miners wanted a state assay office established to allow gold to trade at it fair value. In July a group of citizens met with military governor Col. Richard B. Mason, Jr. to choose assayers to test gold and supervise making gold ingots.

Mason was opposed and no state office was created. In April 1850, another group of businessmen requested that the legislature create an assay service to make ingots of gold at $16.00 per ounce. Later in the month another petition was sent to Governor Peter Burnett asking that Frederick D. Kohler be made the state assayer. On April 20th the state legislature created the office of state assayer. Burnett appointed Frederick D. Kohler as the state assayer and O.P. Sutton as the director. As a result, Kohler sold his private assay business to Baldwin & Co. on May 24, 1850.

While in the assay business it is believed that Kohler and Company made coins for the Pacific Company dated 1849. They were $5.00 and $10.00 pieces.