hronometry and rate regularity are the result of these details. Together, they all contribute. More importantly, they guarantee continuity and consistency over time. There have been other inventive, innovative movements but calibre 7135, which meets all the challenges a watch encounters when worn, sets a very high bar.

Below is a review of the various advancements contained in this next-generation movement.

First, the Dynapulse escapement, which is protected by seven patents. It is designed specifically to optimise the distribution of energy from the mainspring to the oscillator and achieve the greatest possible efficiency by “losing” as little energy as possible. To achieve this, Rolex’s engineers worked on the escapement’s overall architecture, the materials used, the components’ geometry and surface quality. Also, the lighter the whole, the more efficient energy distribution will be.

Architecturally speaking, this is a sequential distribution escapement with energy distributed along a direct line from the barrel. It’s remarkably light because it is in silicon, which is half the weight of titanium, and because of the cutout geometry of the distribution wheels. These wheels have teeth and blades on the same plane. These blades mesh and the teeth alternately, sequentially, interact with the impulse rocker which gives impulse to the balance. This construction of the wheels reduces friction which in turn reduces energy consumption.

This escapement was also designed for a frequency of 5 Hz as opposed to 4 Hz, a first for Rolex. This results in more rapid consumption of the power supplied by the automatic winding system. This had to be optimised in order to maintain a similar power reserve (around 66 hours) to that of the earlier calibre 7140. Beyond the fact this higher frequency could display tenths of a second, and that the seconds hand is smoother, a higher frequency corresponds to better rate stability.

A balance wheel that makes ten vibrations per second, which is the case at 5 Hz, rather than eight, at 4 Hz, is easier to adjust and with greater precision. Back when Rolex was still equipping its Daytona with El Primero movements beating at 36,000 vibrations/hour, it would slow them down to 28,800 vibrations/hour because they were too energy-hungry. Maintaining 66 hours of power reserve therefore implied a number of technical choices.

The oscillator was the subject of considerable attention, starting with the balance staff in ceramic, which Rolex tells us is polished “to nanometric scale”. This is important, as every micron of polished surface represents an infinitely small energy gain. Also, as well as being antimagnetic and extremely strong, which prevents microfissures forming in the event of an impact, ceramic allows for optimal geometry and a perfectly smooth surface state, polished by a femtosecond laser.

The balance wheel is in “optimised brass”, an alloy that Rolex uses here for the first time for its magnetic resistance, which is comparable to that of the ceramic for the staff. This is thinking as a whole, not in parts. Friction must also be reduced, across the entire chain. The geometry of a part, its surface state, lubrication, strength… everything counts.

The Syloxi balance spring is a silicon and silicon oxide composite, hence insensitive or less sensitive to temperature variations, magnetic fields and shocks. Rolex developed a special patented geometry for this balance spring in which the coils become thicker and further apart along its length, thanks to the high-precision Deep Reactive Ion Etching manufacturing process. This innovation ensures regular oscillations in all positions as well as more precise adjustment which compensates for the effects of gravity in vertical positions, where it is strongest.

Calibre 7135 is certified to Rolex’s Superlative Chronometer standard. This means that once the uncased movement has passed the usual tests by the Contrôle Officiel Suisse des Chronomètres (COSC), because casing can cause slight deregulations, Rolex then performs a second series of tests on the cased movement, including additional testing of water-resistance and power reserve, in conditions that simulate real-life wear. Whereas COSC certification requires an average daily rate of -4/+6 seconds, for Rolex Superlative Chronometer certification this variation cannot exceed -2/+2 seconds per day.