Heinrich Köhler 384 Auction – Day 2 Single Lots & Airmail and Zeppelin Mail – inclusive the collection of the Sieger family

1892/97, "On S.S.S." in type 13 on Elephant 6 d. green in vertical pair, imperforated between, unused with part original gum. A unique item. This stamp has not been listed so far in Stanley Gibbons, it's status is unknown. The pair without overprint already is a great rarity (SG23a). Certificate BPA (2013)