Auction #93 Worldwide Air Post stamps and postal history, Zeppelin Flight items, philatelic rarities of the World

1913, Tercentenary of the Romanov Dynasty, Nicholas I, imperforated proof of 15k in brown (issued color) in sheetlet of ten (5x2), printed on chalk- surfaced thin card, Russian letters ''RZ'' (Rihards Zarins - artist of this issue) at bottom right, very fresh and nice, no gum as produced, very lightly hinged at top and bottom, no thins or any hidden defects, VF and extremely rare, ex-M. Liphschutz, G. Denisenko, according to Robson Lowe only three such sheetlets were printed, we sold one of them with minor faults at our Auction #59 (December 2013) for $10,350 including commission, Est. $10,000-$15,000