1853 $20 Assay (1853 Double Eagle) NGC MS63 CAC. This mint state twenty dollar, U.S. Assay of Gold coin has clean, satiny surfaces with subdued mint luster. It is tied for third finest at NGC and comes in an older type holder. The CAC sticker confirms the grade and also indicates that the coin is a premium quality piece that meets stringent standards within the grade. The strike is above average with details on the shield, the eagles neck, and the central portion of the reverse.

The obverse, designed by Charles C. Wright, shows an eagle with wings spread partially behind a rock and shield. Behind one wing and in front of the other is a ribbon, which is inscribed LIBERTY. Above the eagle is a banner with the legend 900 THOUS, which is the fineness of the gold. The design is encircled with the inscription UNITED STATES OF AMERICA with TWENTY D. below. The reverse has a machine pattern with the central inscription UNITED STATES ASSAY OFFICE OF GOLD SAN FRANCISCO CALIFORNIA. 1853.

In 1852 the firm of Moffat & Co. a private minter and assayer was dissolved. A new company took its place called the United States Assay Office of Gold. The principals of this new company were Joseph R. Curtis, Philo H. Perry, and Samuel H. Ward. This second period of private gold coinage took place from 1852 to 1853. The Assay Office assumed the government contract to make gold coins and gold ingots. Augustus Humbert, the former assayer, was told to continue working with Curtis, Perry and Ward. T. Butler King, the Customs Collector, was informed by Treasury Secretary Thomas Corwin to accept the coinage of the United States Assay Office of Gold. The Assay Office was the precursor of the United States branch Mint in San Francisco. The Assay Office struck many ten and twenty dollar gold pieces that were later melted and recoined into regular double eagles.

In February of 1852, the new firm announced reduced rates for coining bullion from less than one percent to two and three quarters percent for ten and twenty dollar coins. Evidently the United States Assay Office of Gold was able to meet the needs of the people of California at the time. However, in April merchants and bankers requested the issuance of a five dollar coin. In September a crisis developed when Customs Collector King was informed by Assistant Secretary of the Treasury William Hodge that he could not receive coins from the United States Assay Office that were under .900 fine. This information meant that California had no legal currency. The reason for this new measure was because the United States Assay Office of Gold was the only obstacle to the passage of a bill authorizing a branch mint in San Francisco. By not allowing Assay Office gold, California Senator Gwin felt that the obstacle would be removed. He also argued that because the coinage of the Assay Office was less than .900 fine, if it entered world commerce, the prestige of the United States would be damaged. At the same time, gold coins of foreign countries such as Mexico and Chile were acceptable regardless of their fineness. In the meanwhile, Curtis, Perry, and Ward were asked to prepare and strike coins that were .900 fine. They agreed and soon .900 fine coins began to appear in commerce. Most had been struck from dies that had struck .880 and were altered to read .900. They issued approximately $360,000 in ten dollar gold pieces and $720,000 in twenty dollar pieces, such as the present coin, per day. At the same time, the Assay Office was asked to coin small denominations for use in commerce. Since there were no parting acids available, Humbert decided to use dies with .880 and .884 THOUS in defiance of the law. He started making these coins early in 1853, but the shipment of parting acids arrived before many were made. A few of this issue are known today. Samuel Ward died in April. Curtis and Perry stopped coinage operations after one final piece, the 1853 MOFFAT & CO twenty dollar gold piece. They ceased operations on December 14, 1853. Curtis and Perry provided both the building and machinery for the new branch of the United States Mint, which began operations on April 15, 1854. Humbert was not kept on as the assayer. He was replaced by Agoston Haraszthy, an assayer who had had experience working with Wass, Molitor & Co.

In its population report, NGC shows 24 U.S. Assay double eagle coins in MS63 with 19 better. At CAC, as of December 2011, there are 4 in MS63 with 4 better.