With its new Ref. 5905P Annual Calendar Chronograph, Patek Philippe proves yet again that refined combinations of trailblazing design and successful horological complications can result in totally new and distinctive timepieces. The metamorphosis begins with the dial that reflects the design of the Ref. 5205 Annual Calendar launched in 2010 but with new colors and further details is nonetheless original and unmistakable. The outermost scale for the chronograph hand is adjoined by a crisply graduated minute scale. It is followed by a broad ring that accommodates the applied white-gold hour markers and – between 10 and 2 o'clock – the three aperture displays of the Annual Calendar. The date aperture at 12 o'clock is somewhat larger and embedded in a polished white-gold frame. At 6 o'clock, it is complemented by a large 60-minute chronograph counter and a small window for the day/night indicator just below the arbor of the hand. This configuration endows the technical aura of the Ref. 5905 with the timeless elegance of a typical Patek Philippe wristwatch. The hour and minutes hands that hover above the dial are fashioned in a novel Dauphine silhouette with three facets and a Superluminova coating on the center ridge. Together with the luminous 5-minute markers, they assure excellent legibility in the dark. The dial is available in navy blue and black versions: Blue underscores the elegance of the watch while black emphasizes its function as a technical time measurement instrument. 

A platinum case crafted entirely in-house 

Both dials harmonize with the cool gloss of the prominent 42-millimeter platinum case. All case contours are formally balanced and nothing distracts from its coherent design. The round profiles of the bezel and caseband merge seamlessly with the gently curved lugs. The outer contours of the start/stop pusher, the crown, and the reset pusher are perfectly arranged along an arc parallel to the caseband. Every detail is rigorously premeditated to please the eye and assure user convenience. The case is crafted from solid platinum 950 in the manufacture's own ateliers and leaves nothing to be desired in terms of form and finissage. Including time-consuming manual processes such as deburring, grinding, mirror-polishing with progressively finer grit, and repeated rigorous inspections, it takes nearly two weeks to produce a case. What starts out as a platinum bar cold-formed in a high-tonnage press ends up as a masterpiece that complies with all directives of the Patek Philippe Seal and fulfills the expectations of discerning Patek Philippe customers. It is a lavishly finished case of flawless beauty; its sapphire-crystal back reveals a mechanical movement crafted with equally uncompromising attention to detail. And like all of the manufacture’s platinum cases, it features a flawless Top Wesselton diamond between the lugs at 6 o’clock. 

A movement with two popular complications 

The round display back exposes the large and heavy 21K gold winding rotor which keeps the Annual Calendar Chronograph running continuously if it is regularly worn. It is artistically decorated as are the bridges – in this instance not with classic straight Geneva striping but instead with circular graining as an extension of the round pattern on the rotor. The noble contrast of gold against the silvery rhodiumed surfaces, the shiny chamfers, and the red bearing jewels endow the caliber CH 28-520 QA 24H movement with a nimbus that will seduce every watch connoisseur. 

It combines the function of a flyback chronograph with that of the Annual Calendar, two highly popular complications. The Annual Calendar is based on a patent granted to Patek Philippe in 1996. The calendar displays are controlled mainly by wheels and pinions rather than rockers and levers: rotary motion is easier to master. Accordingly, Patek Philippe's Annual Calendars have been paragons of functionality and dependability for almost 20 years. The patented Patek Philippe Annual Calendar is a full calendar that automatically recognizes 30- and 31-day months. If the watch runs without interruption, only one manual correction is required each year at the transition from February to March. It displays the day of the week, the date, and the month, and it controls the day/night indicator. The chronograph mechanism of the new Ref. 5905P is just as modern. It remains true to the traditional column wheel for handling the start, stop, and reset commands. However, it controls the clamp of a vertical disk clutch rather than the lever of a horizontal wheel clutch. This solution is characterized by a high degree of reliability. It eliminates the risk of hand bounce or recoil when the chronograph is activated, because it does not rely on meshing wheels. Since the disk clutch works in a practically wear-free manner, the chronograph hand can double as a running seconds hand that does not negatively influence the rate accuracy of the movement. This is why the subsidiary seconds indication, commonplace in most chronographs, was omitted. 

The new Ref. 5905 marks a further step forward in the evolution of Patek Philippe's Annual Calendar Chronographs: thanks to creative fine-tuning, it has a clearly distinctive new look. The manifestly elegant model with the blue dial comes with matching navy blue strap. A matt black alligator strap complements the version with the black dial. Both straps are secured with a platinum 950 prong buckle. 

A short review of the long history of Patek Philippe calendar chronographs 

Patek Philippe wrist chronographs have ranked among the most coveted timepiece types since the 1920s. Hardly any other manufacture devoted so much attention to short-time measurements, not only with respect to technical facets but also as regards the level of perfection in finissage. Even though the movement blanks were sourced from the best external producers for decades, they were hardly recognizable after they had been completed and finished by Patek Philippe. They were like uncut diamonds of the finest quality that revealed their true beauty only in the hands of Patek Philippe's masters. 

Ninety years ago, Patek Philippe was one of the first manufactures that began endowing wristwatch chronographs with additional functions. Presented in 1923, its first wrist chronograph already featured the split-seconds function. A World Time chronograph with a pulsimeter and an asthmometer (respiration rate counter) premiered in 1940. A year later, Patek Philippe began to regularly produce the Ref. 1518 wrist chronograph with a perpetual calendar. Today, this model ranks among the highlights at international auctions. 

Patek Philippe is also acclaimed for its wristwatches with full calendars that apart from the date display the day of the week and the month as well. Particularly sought-after: the perpetual calendar that Patek Philippe first presented as a wristwatch in 1925. And, as mentioned, as a perpetual calendar chronograph in 1941. 

During the last 20 years, Patek Philippe infused fresh impetus into these legendary models, to the delight of the international watch lovers community. 1996 marked the debut of the Patek Philippe Annual Calendar with day, month, and date displays, which only needed to be corrected once a year at the end of February. Its totally new movement architecture made it even more affordable than the manufacture's perpetual calendars. In 2006, Patek Philippe presented the first self-winding chronograph that it had developed and would henceforth manufacture entirely in-house. The special twist: It was combined with an Annual Calendar that perpetuated Patek Philippe's great heritage in calendar chronographs in a new way. This movement, in a new caliber version designated CH 28-520 QA 24H, now runs in the latest model, Patek Philippe's Ref. 5905 Annual Calendar Chronograph.