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A new perpetual calendar for eternityPatek Philippe inspires with complex mechanics and simple elegance

Patek Philippe's Ref. 5320G is a new perpetual calendar for the wrist that has been literally crafted for eternity. It automatically indicates months with 28, 30, and 31 days and every four years also recognizes the 29th of February as a leap day.

And it stands out with a timelessly sleek design, affording a glimpse into the past, present, and future at the same time. Rarely has a perpetual calendar demonstrated its function so aptly. In fact, it is easy to forget that in 2100, a secular year according to the Gregorian calendar, the date display must be corrected by hand.

When the Genevan manufacture presents its Ref. 5320G Perpetual Calendar, the eyes of many haute horlogerie enthusiasts and connoisseurs will sparkle. After all, the new timepiece unites many properties of Patek Philippe's coveted collectors' watches that only rarely show up at major auctions. Indeed, the Ref. 5320G Perpetual Calendar has been inspired by many predecessor models that attracted global attention in the 1940s and 1950s. In 1925, Patek Philippe launched model 97'975, the world's first wristwatch with a perpetual calendar. It was followed by further unique pieces. Eventually, the manufacture integrated this type of watch in its regular collection. The kickoff began in 1941 with the Ref. 1518, a perpetual calendar with a chronograph. A year later, Patek Philippe introduced the Ref. 1526 Perpetual Calendar without a chronograph. Both models were endowed with a face that still thrills collectors: a double aperture for the day and month displays at 12 o'clock and a subsidiary dial at 6 o'clock for the analog date and the moon phases. The cream-colored dial of the new Ref. 5320G adopts the same layout, albeit with further useful indications such as the small round day/night aperture between 7 and 8 o'clock and a round aperture for the leap year cycle with Arabic numerals from 1 to 4 between 4 and 5 o'clock. Applied gold Arabic numerals and five-minute cabochons with luminous coatings, fine-tipped baton hands filled with Superluminova (a reminiscence of the Ref. 1463 chronograph from the 1950s), a slender counterbalanced sweep seconds hand and the crisply graduated seconds scale come together as a paragon of perfect legibility with a face of puristic elegance that conceals the complexity of the mechanical movement beneath the dial.

Proven mechanical ingenuity reinterpreted

The retro-modernistic dial of the Ref. 5320G Perpetual Calendar lies atop a manufacture movement that, like the design of the new timepiece, melds traditional watchmaking artistry with latest-generation technology. The caliber 324 S Q (S stands for seconds, Q for quantième perpétuel – the French term for perpetual calendar) is a refined version of the legendary self-winding movement 324 featuring a large central rotor in 21K gold that delivers remarkable winding power. The new cadrature of the perpetual calendar on the dial side has four additional disks for the aperture displays: day 1 rev/week, month 1 rev/year, leap year cycle 1 rev/8 years, day/night 1 rev/day. The lunar disk behind the analog date at 6 o'clock progresses with the precision of a modern Patek Philippe moon-phae display that requires a single-day correction every 122 years. This corresponds to a miniscule daily error of 0.02 per mil. The bridge side of the movement exposes all of the special features that make a Patek Philippe caliber so remarkable: Bridges with round-chamfered and polished edges, Geneva striping and gold-filled engravings, screws with polished, chamfered slots in bores with polished countersinks, the Gyromax® balance with the Spiromax® balance spring made of high-tech Silinvar®, the solid-gold rotor suspended between ball bearings and decorated with perlage, Geneva circular graining, and an engraved Calatrava cross. The rotor delivers the energy needed to track the progression of time with extreme precision. Its maximum rate deviation ranges between -3 and +2 seconds per day as specified by the Patek Philippe Seal, the Swiss watch industry's strictest set of quality benchmarks.

Time passes, true beauty endures

The modern, highly precise movement is accommodated in an 18K white-gold case crafted entirely in-house, from the design stage to the final polishing phase. It reflects the same vintage style expressed by the architecture of the dial and totally represents state-of-the-art technology. A so-called box-form sapphire-crystal glass was chosen to keep the case flanks slender and endow the watch with a contemporary vintage look. It visibly extends across the bezel and is dramatically cambered with parallel inner and outer sides to prevent optical distortion of the dial regardless of the viewing angle. In the 1940s and 1950s, it would have been technically impossible to craft such a sapphire crystal to current quality standards. This is why easily formable plexiglass was often chosen, despite its susceptibility to scratching, clouding, and cracking.

As regards other case elements, Patek Philippe's creation department sought inspiration from a role model crafted in-house over 60 years ago. It is the Ref. 2405 with a prominent three-tiered lug profile. The design makes them look slender and adds a touch of dynamic appeal to the case silhouette. With the flat center portion, the beveled, smoothly polished bezel overarched by the cambered crystal and the cascading three-tier lugs, the new Ref. 5320G very elegantly hugs the wrist. The watch has a sapphire-crystal case back that reveals the beauty of the mechanical movement. On request, it can be replaced with a solid 18K white-gold back that comes with the watch.

The contemporary vintage style of the new Ref. 5320G Perpetual Calendar is underscored by the shiny chocolate brown alligator strap with large square scales. It is hand-stitched, lined, CITES-certified, and secured with a Calatrava cross fold-over clasp in 18K white gold.

With the new Ref. 5320G Perpetual Calendar, Patek Philippe revisits a grand tradition that the manufacture established in 1925 with the first perpetual calendar for the wrist. Designated with inventory number P72, it belongs to the collection of the Patek Philippe Museum where it can be personally admired.