Baden 9 Kreuzer Error

The Baden 9 Kreuzer Error is a postage stamp error issued in 1851 by Baden, a historical German state. On May 1, 1851, Baden released its first postage stamps. The "9 Kreuzer Green" stamp was a color mistake of the denomination 9 Kreuzer, which was issued in green rather than pink. The green color was supposed to be for the 6 Kreuzer value, however the paper sheets were evidently misaligned. This error has only three canceled copies and one unused copy, but additional sheets of paper may have been printed. The cancellations "4" for Achern, "41" for Ettenheim, and "106" for Orschweier were recorded (today Mahlberg). There are two known examples of letters.

The most common explanation for this inaccuracy is that the printing plate was reversed accidently; nevertheless, this argument cannot be valid because the stamp was only printed once. It's safe to believe that the printer used the wrong plate for the green paper by accident: instead of a "9," he read a "6." It was sold for €1,314,500 ($1.5 million) at auction in 2008.

Price: $1.545 million