German Sea Post Ozeanreederei. 1916, 15M grey, showing the very rare variety watermark lines falling "fallende Stufen", extremely fine and fresh example, mint never hinged original gum. Probably unique in this condition; signed Kosack (Michel unpriced, and we would estimate a catalogue value of €25'000). (Image)

1916, 100M brown violet on gold, showing the very rare variety watermark lines falling "fallende Stufen", extremely fine and fresh example, mint never hinged original gum, probably unique in this condition; signed Kosack (Michel €25'000). (Image)