Patek Philippe’s 2025 Grand Complications Keeps Things Simple

Adding a split-seconds chronograph function to the existing Patek Philippe Caliber R CH 27 PS QI used in the Ref. 5208 is a major challenge because of the added energy resources needed to drive the splitting of the elapsed seconds, and its further rejoining during an event timing. This typically doubles the chronograph’s resource use in a movement. Patek Philippe’s research team had to achieve this without a significant dip in the amplitude of the balance which would not only affect the chronograph, but overall timekeeping. A second challenge was ensuring that two horizontally coupled chronograph seconds wheels would mesh smoothly with the timekeeping gear train to prevent any “bounce” or backlash both during the split, and when running together. To start, the team worked on a new barrel arbor that could support a strong mainspring. With a thicker spring, this provides greater torque and provides more power to the system, guaranteeing an autonomy of up to 48 hours with a split-seconds chronograph. To improve winding efficiency, a platinum micro-rotor is used instead of gold.

The split-seconds chronograph uses a highly impressive and inventive solution to reduce the thickness of Patek Philippe’s isolator found in its CHR 29-535 PS and PS Q movements. The isolator lever (colloquially called the ‘octopus’) has been shrunk down thanks to a dual-lever system that engages the isolator clamp and raises the split-seconds lever from the heart cam of the chronograph. The bi-directional lever means that it can be activated at any position, and is powered solely by the triggering of the split-seconds pusher on the crown. This therefore relieves any additional energy required to add the complication, and only adds 1.93mm of thickness to the movement compared with the Caliber R CH 27 PS QI. Additionally, a newly designed clutch wheel that has long slotted teeth with a spring strip that ensures smooth meshing of the chronograph wheels with the gear train. That includes scenarios when the teeth of the chronograph seconds wheel initially engage between the spring and tooth of the backlash compensation wheel. Its flexibility, produced using LIGA manufacturing ensures it adjusts to the optimal meshing under any circumstances.

Instead of designing a movement that would only be used for the desk clock, Patek Philippe developed a watch-sized precision regulator caliber, that is driven by three going barrels that are connected in series outside of the regulator movement. The power drawn from these barrels is managed via a constant-force mechanism that releases energy to the regulator by the minute. This ensures that consistent power is delivered whether the barrel spring is fully wound, or nearly unwound.

One of the challenges of this clock is the use of sterling silver for the case, combined with Grand Feu flinqué enamelling. Silver has a close melting point of 800°C, and temperatures above this are needed for a great firing in the kiln. To prevent deformation, counter-enamelling was done on the reverse of the panels. The translucent green enhances the guilloché work done on the clock’s cabinet, which is further detailed with winged lions, rosettes, and scrollwork around the Calatrava cross. Gold and green create a royal presence for the clock.

Twenty-five years ago, Patek Philippe developed its first wristwatch with exceptionally long power reserve, the Ref. 5100 Gondolo with 10-Day Power Reserve and with chronometer standard accuracy. This was especially challenging as the Gondolo calls for a fitted rectangular movement to match its case. The Ref. 5100 was succeeded by the Ref. 5200 in 2013 with instant jumping day and date, powered by the Caliber 28-20 REC 8J PS IRM C J with eight days of autonomy. With the Ref. 5328G-001, it shows just how much has changed within the watchmaker, and how consistent it is, across a quarter of a century.

Like its earlier rectangular siblings, the Ref. 5328G shows all its information along the vertical axis, with the power reserve on top and date counter coupled with weekday window and running seconds below. The textured blue dial keeps to the Ref. 5326G-001 Calatrava Pilot Travel Time’s vintage camera-inspired finish, with a black-gradient rim, applied luminous Arabic hours and stylised syringe-hands. The caseband features a hobnail guilloché pattern and lugs that are attached on the back of the case. It also comes with two straps, in blue calfskin with a fabric texture and in grained taupe calfskin, fitted on a new patented clasp that makes it easier to swap out one for the other.