A paragon of visual balance and legibility, the perpetual calendar model bearing Reference 5320 was designed in 2017 in a white gold case with a cream-lacquered dial. Its vintage style is reinterpreted in a new white gold version fitted with a gilded opaline rose gold dial. The calendar displays are arranged in the characteristic manner of Patek Philippe perpetual calendar watches since 1941, with a twin in-line day/month aperture at 12 o’clock and a date indicated by a hand surrounding a moon-phase aperture at 6 o’clock. These are complemented by two round apertures: one for the day/night indication between 7 and 8 o’clock; and the other for the leap-year cycle between 4 and 5 o’clock — both of which are useful to adjust the calendar. The extremely accurate moon phases require a one-day correction only once every 122 years.

Watch
Self-winding mechanical movement. 
Caliber : 26-330 S Q. 
Perpetual calendar. 
Day, month, leap year and day/night indication in apertures. 
Date by hand. 
Moon phases. 
Sweep seconds.
Dial : Rose-gilt opaline, charcoal gray gold applied numerals with luminescent coating.
Case : White gold. 
Diameter: 40 mm. 
Height: 11.13 mm. 
Water resistant : 30 m. 
Sapphire crystal case back.
Strap : Alligator leather with square scales, hand-stitched, shiny chocolate brown. 
Fold-over clasp
Diameter: 32 mm. 
Thickness: 4.97 mm. 
Number of parts: 368. 
Jewels: 29. 
Power reserve: min. 35 hours - max. 45 hours. 
Winding rotor: 21K gold central rotor. 
Balance: Gyromax®. 
Vibrations/hour: 28 800 (4 Hz). 
Balance spring: Spiromax®. 
Hallmark: Patek Philippe Seal.