F. D. Kohler, Assayer

The discovery of gold in 1848 at Sutter’s Mill spurred a great wave of migration to California. Hundreds of thousands of people traveled to the territory from around the world to strike it rich. Competition for mining stakes led to tensions among the gold seekers, often resulting in discriminatory actions toward the Chinese. Increasing competition and varied pricing for gold resulted in the creation of the Office of State Assayer, Melter, and Refiner of Gold by Governor Peter Burnett, which tested the ingredients of gold and produced ingots stamped with their value.

Frederick D. Kohler, a jeweler and volunteer fire fighter from New York City, moved to California in 1849 and started a private assayer firm with David C. Broderick. When the State Assay Office was created, Governor Burnett appointed Kohler as California’s first and only State Assayer on April 20, 1850. Approximately 5,000 ounces of gold were deposited with Kohler on the first day that the State Assay Office opened, with larger quantities following including several counterfeit nuggets. Congress soon replaced the State Assayer Office with the United States Assayer Office in 1851.

Frederick D. Kohler was at the time, President of the Democratic Executive Committee of San Francisco and Chief of the Fire Department!

As the ONLY entity operating similar to a mint that existed outside of the Federal US Government, this State Assay Office was in unchartered new territory. States couldn’t issue money according to the constitution but they could issue Assay Ingots. These could be used for state taxes and local dues but were not officially legal tender. These ingots became known as ‘slugs’ and Kohler’s bars became popular in trade for approximately 5 years.

The State Assay Office at San Francisco was opened on May 13th, 1850 by Frederick Kohler. His ingots proved to be very useful to miners and merchants but many bankers refused to redeem them at full value which created quite a problem.

Each of Kohler’s ingots has the Sate Assay Office stamp, the year of manufacture for which all are 1850, the fineness of the gold in carats, weight in pennyweights, and the value. Only 4 ingots have been seen in recent history. According to the book ‘Private & Pioneer Gold Coins of the United States 1786-1862’, the $50 Kohler slug is the earliest piece in the US Series.

On September 30th 1850 Congress established the USAO officially in San Francisco rather than it being officially a branch mint. As such, the State Assay Office wound down and officially decommissioned as of January 28th, 1851.

Kohler replaced August Humbert, May 28 1853 as United States Assayer. He began running an advertisement stating he was working out of Wass, Molliter & Co.’s Commercial st. San Francisco.


$45.34 – F. D. Kohler – STATE ASSAYER – CAL – 1850 Gold Ingot 21 1/2 Carat

The State of California sometime later, opened a second Sate Assay Office in Sacramento California. From this mint only one known ingot was issued according to Kagin’s book published in 2023, ‘America’s Golden Age: Private & Pioneer Gold Coins of the United States 1786-1862.’ This example would be the 1850 $36.55 FD Kohler Ingot, which now sits in the Smithsonian in Washington DC.


$36.55 F. D. KOHLER / STATE ASSAYER / SAC. / CAL. / 1850 / 20 CARAT / 42 DWT. / 12 GRS. / $36.55 CTS

Courtesy the National Museum of American History at the Smithsonian Institution

In June 1850, the state of California started a second State Assay Office at Sacramento – the example pictured above. This ingot is the only known surviving example from that office and is known to be genuine.

There was a second example discovered by John J. Ford sometime in the mid-20th century but it was unverifiable and due to the controversy of numismatist John J. Ford along with no direct evidence to tie it directly to the Assay Office, it is considered a fantasy piece from the ford collection – it does not directly punch-link to any known Assay Office ingots.

PCGS has identified the following denominations in their census:

  • 1850 $36.55 FD Kohler Ingot
  • 1850 $37.71 FD Kohler Ingot
  • 1850 $40.07 FD Kohler Ingot
  • 1850 $45.34 FD Kohler Ingot
  • 1850 $47.71 FD Kohler Ingot
  • 1850 $50.00 FD Kohler Ingot
  • 1850 $54.09 FD Kohler Ingot

See: https://www.pcgs.com/coinfacts/category/territorial/california-gold/california-gold-ingots/1748


The National Museum of American History has a few Kohler ingots, but the authenticity of one has been called into question. A careful student of these will quickly notice obvious differences between the genuine and counterfeit example.

Unfortunately many of the ingots sold to the Smithsonian from the Josiah k. Lilly Jr. Collection came from Ford, and many of the ingots were counterfeit – total fabrications. It is believed the $41.68 version is one such example.

F. D. KOHLER / STATE ASSAYER / CAL 1850 / DWT. 46 / CARAT 21 3/8 / CTS $41.68

Courtesy the National Museum of American History.

*** As noted above, the authenticity of this piece has been called into question.

See: https://americanhistory.si.edu/collections/nmah_1101603