United States, Airmail, 1918, 24¢ carmine rose & blue, plate block of 12. Two P#, arrow & two "TOP", very scarce used example, centered F-VF and with some hinge reinforcement on reverse, F.-V.F. Scott No. C3  Estimate $750 - 1,000. $0 (Image)

United States, Airmail, 1918, 24¢ carmine rose & blue, May 15, 1918 First Trip. On legal size cover, stamp with tear, cover with some toning and couple vertical folds; also May 23, 1918, 10th trip from NY to DC, cover with vertical fold, F.-V.F. Scott No. C3  Estimate $100 - 150. $0 (Image)

United States, Airmail, 1918, 24¢ carmine rose & blue, center inverted. Position 17, full o.g., which is relatively lightly hinged, rich colors which are bright and fresh, pencil notation on back noting position, faintest trace of diagonal crease, which is barely visible from reverse only, Fine; with 1974 and 1989 P.F. certificates. Scott No. C3a  $500,000. A Rare Example of the Famous 1918 24-Cent Inverted "Jenny" Error and a gorgeous copy of this Classic World Gem.According to "Jenny" by George Amick (Amos Press, 1986), the original sheet of 100 Inverted "Jenny" stamps was purchased for $24 by William T. Robey at the New York Avenue Branch Post Office window in Washington D.C., on May 14, 1918, one day after the stamp was first placed on sale at the main post office. On May 20, Robey sold his sheet for $15,000 to Eugene Klein, a Philadelphia stamp dealer. Klein had already arranged to sell the sheet to Col. Edward H. R. Green for $20,000. Colonel Green instructed Klein to divide the Inverted "Jenny" sheet into singles and blocks, and to sell all but a few key position blocks. . $0 (Image)