U.S. and Worldwide Stamps and Postal History

1933 Balbo Flight Surcharge, $4.50 on 75c yellow brown, partially doubled surcharge, clearly visible in the numbers of the date and value (partial offset of the surcharge on reverse as well), position 1 of the setting and the only one recorded unused (there was an example used on cover in the Cyril Harmer collection), small surface mark at left (seems to be from the surcharging process), very fine in all respects, 2010 BPA certificate (Unitrade C18iii, listed but unpriced)
Estimate: $25000