Extremely rare Swiss gold World Time dress watch Circa 1948

World Time watch with a Map of North America dial by Patek Philippe  
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An excellent and rare Swiss pink gold open faced keyless lever world time watch with a cloisonné enamel map of North America, circa 1948. This rare watch features a cal. 17-170 HU damascened movement with lever escapement, 18 jewels, a bimetallic compensation balance, and precision swanneck regulation. It is signed and numbered by Patek Philippe & Co. 930864. The dial is cloisonné enamel, showcasing a map of North America with a palm tree to the lower left and a ship to the right. It has applied pink gold Roman numeral and dot hour indexes, surrounded by a two tone revolving 24 hour ring divided into day and night hours. The outermost satin finished revolving ring is marked with 41 world locations and also displays 24 hours. The dial is signed Patek Philippe, Genève.
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The 18k pink gold case features a revolving, polished, chamfered bezel with a finely milled edge, rounded case sides, and a snap-on back with a broad, chamfered, polished rim and a satin finished flat centre. It also has a polished bow, and the case back is signed and numbered by Patek Philippe & Co., Genève, 654.949.
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Diameter: 44.5 mm
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Signed: Patek Philippe & Co. Genève
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The movement is running and in good aesthetic condition, with clean screw heads and plates. The revolving 24 hour ring functions appropriately in conjunction with the hand setting. The case maintains well defined angles and edges, although it has been lightly refurbished. The dial is in excellent condition and displays vibrant enamel.
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The Heures Universelles watches are among the most sought after of all Patek Philippe’s vintage productions, and examples of these timepieces are often the centrepiece of some of the world’s most prestigious watch collections. 
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Reference 605 was one of the earliest models to feature the innovative world time system developed by the renowned watchmaker Louis Cottier. Production began in 1937 and continued for about thirty years, during which fewer than one hundred examples were made. Research indicates that approximately three quarters of the Ref. 605 watches were delivered in yellow gold cases, while about one quarter were made in pink gold. 
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Initially, the model was produced with plain metal satin finished centres in champagne, pink, or silver shades. However, in the late 1940s, Patek Philippe began to commission a small series of richly coloured cloisonné enamel dials. These cloisonné dials typically featured stylised “maps” of the continents, including representations of the Americas (either North alone or both North and South), as well as larger world views combining Europe with Africa and Asia or even a complete world view.
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Cloisonné enamel dials are especially prized by collectors for their distinctive designs and vibrant colours, which remain undimmed by the passage of time thanks to their enduring finish. The appeal of the cloisonné dial is further enhanced by the fact that each one is unique; since they are hand painted, subtle variations occur in tonal colouration, as well as the inclusion and placement of details and motifs.
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The Heures Universelles function in Reference 605 is operated via the bezel, a mechanism also found in the wristwatch Reference 1415. To set the watch, the user rotates the bezel until their current location is aligned with the twelve o’clock position and then adjusts the hands to show the correct local time. The recessed 24 hour ring is automatically geared to turn as time progresses, allowing it to indicate the correct time in all time zones around the world.
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Since the case, dial, and movement are all integral to the watch’s technical function, Louis Cottier supervised the production of each component. Interestingly, like many of Cottier’s inventions, this watch lists London and Paris in the same time zone, Greenwich Mean Time (GMT). However, on June 15, 1940, Paris switched to Central European Time due to the war. For many years, it was believed that Paris would eventually revert back to GMT, and there are Patek Philippe Heures Universelles watches and wristwatches from as late as the 1970s that still list Paris and London in the same time zone.
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Louis Cottier (1894-1966) was born in Carouge and attended the Horological School of Geneva before beginning his career alongside his father, Emmanuel Cottier (1858-1930), also his horological mentor. Like his father, Louis was a talented mechanical genius and developed numerous patents that significantly impacted the field of watchmaking. 
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In response to the challenges posed by the Great Depression, Cottier identified a niche in high end watchmaking. He dedicated his skills to creating complicated timepieces for prestigious brands such as Patek Philippe, Agassiz, Rolex, and Vacheron Constantin. One of his most important inventions was the world time mechanism, developed in the 1930s. This groundbreaking innovation would inspire some of the most iconic complications created by Patek Philippe.