10c Ultramarine, Special Delivery, "Pink Back" (E11 var).
Mint N.H., gorgeous color, Jumbo margins with essentially perfect centering, Extremely Fine Gem, with 2004 P.S.E. certificate (Superb 98; SMQ $725.00 as normal with no premium for the Pink Back), only three have graded higher (probably not the variety though), a footnote in Scott states that Pink Backs are "valued at approximately five times more than the normal stamp", Scott Retail as normal
Image Magnifier / Download
Power Search for Comparables