Swiss complicated watch with perpetual calendar Circa 1922

Rare pink gold open faced lever pocket watch by Breguet
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An exquisite and exceptionally rare Swiss pink gold open faced, two train perpetual calendar chronograph watch featuring jumping fifths, a retrograde date, and moon phases, circa 1922. Originally sold to Monsieur Jean Dollfus on July 12, 1922, for 6,500 francs.
This watch features a 20”’ frosted gilded movement with a two train mechanism and tandem keyless winding for its two barrels. It includes a lever escapement, jeweling up to the centre, a bimetallic compensation balance, and precision cam form regulation. The chronograph seconds and jumping fifths are activated via a push button integrated into the crown. The white enamel dial showcases Roman numerals, an outer Arabic minute ring, and an outermost track for chronograph seconds. It also includes a retrograde sector for the date, apertures for the day and month, and a distinctive oval aperture with a fixed disc depicting a night sky, featuring a central circular opening for moon phases. Additional features include a sunken subsidiary dial for jumping fifths of a second, blued steel hands, a pink gold date hand, and a chronograph seconds hand with a fleur-de-lys tail.
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The 18 carat pink gold polished case is designed with a rounded bezel and includes a pusher on the left side of the pendant for quick day and date adjustments in tandem. An olivette on the right side allows for hand adjustments. The polished hinged cuvette features milled borders and is signed and numbered as Breguet No. 4420, with further numbering inside the cuvette and case back reading 2913. Accompanied by a Breguet certificate dated 27 January 2020.
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This watch is a brilliant and intricate creation, emphasising visual clarity. This is accomplished by using apertures instead of subsidiary dials for day and month indications, complemented by an arcform retrograde date display. The chronograph derives its power from an independent train. A crown mounted pusher initiates, halts, and resets both the chronograph seconds hand and the flying fifths subsidiary seconds dial.
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Diameter: 53 mm
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Signed: Breguet 
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The movement is running smoothly. All calendar functions are advancing as expected, with the adjuster pusher and handset fully operational. The dial is in good overall condition, while the case shows minor signs of light polishing.
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Brothers Jean (b. 1884) and Louis Dollfus (b. 1901) were key patrons of Breguet, buying significant complication watches in the 1920s. They belonged to the prominent Dollfus-Meig et Cie textile manufacturing family, founded in 1746 in Mulhouse, France. During the 20th century, they were among Europe’s largest industrial groups. The piece bought by Jean Dollfus is one of the earliest Breguets acquired by either brother, showcasing features that likely sparked their interest in collecting. Their collection included Tourbillons nos. 986 & 1389 (sold 1926 & 1927), Pocket Chronometer no. 472 (1924), Two Train Chronometer Clockwatch no. 680 (1926), Chronoscope no. 1285 (1926), Platinum dress watch no. 4344 (1929), Split seconds chronograph no. 2170 (1929).