Will An Inverted Jenny Turn The Stamp World Upside Down Again?

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This weekend, on Sunday, September 22, 2013, the William H. Gross Stamp Gallery at the Smithsonian National Postal Museum opens to the public. The gallery has been in the works since the fall of 2009, when Gross, who made his billions as the founder of the Pimco Total Return bond fund, donated $8 million to the National Postal Museum.
Among the 20,000-plus items on display is a block of four 24-cent Inverted Jenny stamps, so named because the blue intaglio vignette of a Curtiss JN-4-H biplane in the 1918 stamp was printed upside down in relation to its carmine-colored frame.
(thanks Ben)