115P3, 6c issue of 1869 plate proof on india

The 1869 National Bank Note Pictorial Issue was the first set of United States stamps printed in two colors. The set featured ten different denominations, ranging from 1-cent to 90-cent. The 15-cent through 90-cent denominations were bi-color stamps. The nearly square stamps went into circulation around March 1869 and remained in use for a little less than a year. The public disliked the stamps for reasons including design, shape, and the ineffectiveness of the gum in affixing stamp to envelope. Because the 1869 Pictorial Issue was the first and last issue to employ multiple colors until 1918, it is considered one of the highlights of the entire Classic Period of United States philately.

Proof: Any print, not a stamp sold by the Government, printed from an officially approved design die or plate at any time during the existence of the die or plate, is a proof, no matter in what color, or material upon which it may be printed for experimental purposes. All essays and proofs are printed only by the proof printer, or proofer, on a hand press.