Pocket watch/pendant watch: Rolex rarity, ultra-thin observatory chronometer 'Prince Imperial' with black dial, Ref.8753 , from the 1950s: Ca. 37 × 42mm, ca. 40g, 18K gold, Reference number 8753, manual winding, ultra-thin chronometer calibre, marked 'Observatory', No. 3677, adjusted in 7 positions, fantastically preserved black dial, gold hands, in working order, in very good condition, extremely rare with black dial. To our knowledge, only 2 other pieces with black dial have appeared on the market in recent years: 1. Auction Geneva (https://www.cortrie.de/go/91e), sold for 13,750 Swiss Francs. 2. Switzerland (https://www.cortrie.de/go/5PZ), sold, price unknown.