Dag Hammarskjöld invert
The Dag Hammarskjöld invert is a 4-cent value postage stamp error issued on 23 October 1962 by the United States Postal Service (then known as the Post Office Department) one year after the death of Dag Hammarskjöld, Secretary-General of the United Nations, in an airplane crash. The stamp, showing the yellow background inverted relative to the image and text, is also known as the Day's Folly after Postmaster General J. Edward Day who ordered the intentional reprinting of the yellow invert commenting, "The Post Office Department is not running a jackpot operation."
- Country of Production = United States
- Location of Production =
- Date of Production = 23 October 1962
- Nature of Rarity = Invert error
- Number in Existence = 40,270,000
- Face Value = 4-cents US$
- Estimated Value = US $0.50
The stamp reprint was in effect a deliberate error produced by the Post Office Department to avoid creating a rarity. It was decided to reprint 40 million of the inverted stamps after the discovery of the error so there would be no rarity factor in the inverted stamp and to prevent people profiting from the Postal Service's mistake. The reprints were issued to the public on 16 November and described as a Special Printing.
The black, brown and yellow commemorative stamp with yellow background correctly printed has a Scott catalogue number of 1203 but the inverted error is numbered 1204. The catalogue value of the invert is worth little more than the normal. The stamp, printed on Giori press in plates of 200, was designed by Herbert Sanborn and engraved by C. A. Brooks. 121,440,00 normal stamps were printed and 40,270,000 of the inverted reprint were produced. It has not been recorded how many original invert stamps were produced and it is virtually impossible to tell a reprint from an original unless it has a clear early date, but an invert error on a first day cover, proving that stamp was from the original printing and not from the reprint, was sold in 2005 for US $3,500.
The discovery sheet, owned by Leonard Sherman, a New Jersey jeweler, donated his sheet to the American Philatelic Society in 1987 because the reprint dashed his hopes of owning a valuable stamp error.
-  Linns: Errors versus errors, freaks and oddities (retrieved 29 September 2006)
-  First day of issue in Robert Siegel 2005 auction (retrieved 29 September 2006)
-  Dag Hammarskjöld On Stamps by Chuck Matlack (retrieved 29 September 2006)
- The American Philatelist, It's a really Big Shoooow!, Barb Boal, August 2004, p863, APS, ISSN 0003-0474