Beginning as jewelers and watchmakers in San Francisco, the firm of Baldwin & Company entered the private coining business on March 15, 1850, led by partners George C. Baldwin and Thomas S. Holman after taking over F. D. Kohler & Company's operations. It was not until May that Baldwin & Co. posted a notice advertising their assay, refining and coining business. In short order, Baldwin & Co. was producing prodigious quantities of $5 and $10 gold pieces. The dies were finely produced and were almost certainly the work of noted engraver Albert Kuner. By early 1851, the San Francisco Herald reported that Baldwin & Co.'s output nearly matched that of the United States Assay Office of Gold.

The firm's $5 coin closely resembles the federal half eagle, but the 1850 $10 bears Kuner's famed "Vaquero" obverse with a mounted cowboy swinging a lasso. In 1851, the firm added $20 gold pieces to their repertoire and circulation continued, with most merchants accepting the coins at par. This all came to a quick end when James King of William submitted samples of each denomination to Augustus Humbert for assay. Humbert reported that the Baldwin pieces were underweight: the $20 piece had $19.40 of gold, the $10 only 9.40, while the $5 coin fared better with a valuation of $4.91. Even though some weight discrepancies could reasonably be expected, the assay and the subsequent news reports had a deleterious effect on Baldwin's business. Branded a "short-weight gold swindle," the pieces were driven from circulation, as businesses refused to accept them except at a steep discount. Although Baldwin tried to counter the accusations with a more favorable assay from Kohler, the damage had been done and on April 15, 1851, Baldwin closed up shop and left California on the steamship Panama. As a result of the constant denunciations, not only did almost all of the Baldwin & Co. coins end up in the melting pot, so too did most of the other private coiners' products. Now, Baldwin & Co. coins are prized by numismatists who are attracted to pioneer California gold. Very few exist in any grade and undamaged specimens are especially elusive.

The example to the left was sold by Stack's Bowers Galleries in the March 2017 Baltimore Auction, where it realized $32,900.