Early U.S. currency designs featured complex engravings that were printed with black ink on the face and a colored ink, generally green, on the back. This gave the notes beauty and distinction and made counterfeiting difficult. The engravings and colored inks also occasionally provided notes with nicknames.
The Series 1890 $100 Treasury Coin Note was nicknamed the “Watermelon Note.” The name came from the design on the back in which the “0s” in the large“100” featured a pattern resembling a watermelon rind. The design, as well as the green ink, made counterfeiting difficult. A portrait of Civil War naval hero Admiral David G. Farragut appeared on the face.
The back of the Series 1882 Gold Certificate featured an ornate, golden-orange “C,” the Roman numeral for 100. The brilliant color was also a useful counterfeit deterrent and led to the nickname “gold back” for Gold Certificates. Also, the use of the numeral “C” was the source of the nicknames “C-note.” A portrait of Thomas Hart Benton, member of the U.S. Senate (1821-1851) and the House of Representatives
(1853-1855), appeared on the face.