Los-Nr. 503

10 c. bright blue, block of 4 with clear to mostly large margins, nice fresh colour, unused with original gum; at right a faint vertical crease/bend and a slight buckling in the lower center, still fine and fresh; most likely the finest unused block in existance, sign. FSPL and Goebel, certificate Böttger BPP (2017) Provenance: Maurice Burrus (1963)