A couple of years back, Vacheron Constantin unveiled a true masterpiece of virtuosity in which the complexity of the striking mechanism was matched by the additional challenge of creating the thinnest hand-wound calibre and the thinnest hand-wound minute repeater watch on the market, at respectively 3.9 and 8.1 mm thick. Initially introduced in 18K 5N pink gold, this timepiece is now available with platinum case – framing a silvered opaline or slate-colored opaline dial – bearing the prestigious Hallmark of Geneva.
In an act that was to spark its longstanding love affair with striking watches, the Manufacture Vacheron Constantin created its first minute repeater mechanism for a pocket watch, before combining striking mechanisms with other major horological complications throughout the subsequent decades. In doing so, it repeatedly created exceptional timepieces that were some of the most complex of their era.
Watches that have gone down in history, such as the watch made for King Fouad of Egypt in 1929, or the one created for his son, King Farouk, in 1935. In 1941, Vacheron Constantin launched its first wristwatch equipped with a single complication in the shape of a minute repeater housed in an ultra-thin movement: Calibre 4261. The quest for extreme slenderness continued through subsequent years, and in 1992, the Manufacture once again pushed back the boundaries of feasibility by presenting Calibre1755, a minute repeater movement just 3.28 mm thick. In 2013, Vacheron Constantin released a new movement paying homage to this emotionally charged complication: Calibre 1731, thus named in tribute to the birth year of the Maison founder, Jean-Marc Vacheron.
Calibre 1731 is barely thicker – due to an impressive 65-hour power reserve – than its predecessor from 1992, measuring a mere 3.90 mm compared with the original 3.28 mm. It indeed remains the thinnest on the market to this day, having brilliantly overcome the difficulty of assembling and adjusting such supremely slimmed-down components. Four years were needed to solve the highly complex conundrum of creating a new minute repeater movement mingling slenderness, pure sound, aesthetic beauty, reliability and sturdiness. Nor are the technical feats confined to its ultra-thin side of nature, since Calibre 1731 is equipped with an extremely ingenious device: a flying strike governor developed by Vacheron Constantin in 2007 for the 2755 movement, another member of this highly exclusive family of minute repeater calibres. Unlike classic lever-type governors, this one is entirely silent. Its role is to steady the rate at which the hammers strike the gongs. Without such a governor (also known as a regulator), this musical sequence would play at the speed of the striking barrel-spring and would thus produce a series of indiscernible notes. The device developed by Vacheron Constantin comprises two inertia-blocks or weights designed to act as a brake on the rotating shaft of the governor and thus evening out the energy supplied by the barrel spring. It achieves this by making use of opposing centrifugal and centripetal forces. When the governor spins, centrifugal force pushes one end of the inertia-blocks outwards, while the other end presses on the shaft to slow it down and stabilise the rotation speed in order to ensure a steady cadence. Perfectly finished right down to the smallest details, the governor bears Vacheron Constantin’s Maltese cross emblem, even though this motif cannot be seen from the front of the calibre.
Particular care was devoted to the acoustics of the Patrimony ultra-thin calibre 1731, since the sound of a striking watch is its very reason for being. Various technical choices were made to ensure a crystal clear and perfectly tuneful tone. The gongs are not only connected to the case middle so as to amplify the sound, but also for the first time stacked rather than placed side by side. The platinum case is shaped so as to form a unified whole with the movement, within a clever composition incorporating such subtle parameters as the airflow between the mechanism and the case, designed to achieve optimal propagation of the notes. Nor does the quest for perfection end there, since the case itself has been built without joints so that the elements can interact metal against metal and thereby enhance the amplitude of the sound, while the flying governor ensures a regular rate of the hammer blows on the gongs.
While each master-watchmaker instils his own music into the minute repeater that he will take several months to assemble and adjust, the sound of the movement will be submitted to the keen ear of the virtuoso striking-mechanism specialists of the Manufacture, and will undergo any adjustments needed to achieve perfect harmony between the low-pitched and high-pitched notes. And it is precisely at 4:49 that the tests are performed, since that is the time when the cadence is most clearly audible due to the almost identical intervals between the hours (four strikes), quarters (three strikes) and minutes (four strikes).The true living soul of a minute repeater watch, the individual chime of each watch is recorded and carefully stored before the timepiece leaves the Manufacture, thus constituting a “soundprint” duly registered in the archives of Vacheron Constantin. The latter guarantees not only the lifelong repair of all its watches, both historical and contemporary, but also the ability to restore within its workshops the unique sound of each model equipped with a minute repeater.
Testifying to an ancestral expertise that sets an authentic Haute Horlogerie creation apart from the rest, the components of Calibre 1731 are patiently hand-finished one by one, even though some will remain hidden. Whereas the mainplate is circular-grained, the hammers are specular polished to as to alternately catch the light of appeared clothed in a deep black cloak so as to eliminate any trace of the finely worked surface. Meanwhile, the bridges are adorned with a delicate Côtes de Genève pattern creating a refined wave effect. While the artisans of the Manufacture Vacheron Constantin are well accustomed to the various finishing techniques, there is one in particular that requires a highly demanding 18-month training period: bevelling or chamfering, meaning the specific work on the reentrant angles, such as can notably be found on the seven bridges of Calibre 1731.
The design of Patrimony ultra-thin calibre 1731 is inspired by an ultra-thin model created in 1955 to mark the Vacheron Constantin bicentenary and then revived in 2004 to give life to the Patrimony reference 81180. Since then, its extreme slenderness, its pebble shape, its curved bezel, its cambered dial and crystal, its beaded minute circle, along with its baton-shaped hands sweeping over alternating triangle and baton-shaped hour markers, have established it as a timeless classic. While the Patrimony ultra-thin calibre 1731 has remained true to its iconic design codes, its platinum case has been the object of subtle and complex workmanship so as to form a unified whole with Calibre 1731 and to set a double record: the thinnest hand-wound minute repeater movement (at 3.9 mm), driving the thinnest hand-wound watch (8.1 mm).
The curve of the case middle has thus been accentuated so as to further trim down the silhouette, while the sapphire crystal caseback has been opened as broadly as possible to reveal the hammers, along with a rare glimpse of the gongs. On the dial side, Vacheron Constantin has opted for an extremely elegant small seconds offset at 8 o’clock, a useful and playful way of making the Patrimony ultra-thin calibre 1731 immediately recognisable.
Patrimony ultra-thin calibre 1731
References: 30110/000P-9999 & 30110/000P-B089
Hallmark of Geneva certified timepieces
Developed and manufactured by Vacheron Constantin
32.8 mm (14’’’1/4) diameter, 3.9 mm thick
Approximately 65 hours of power reserve
3Hz (21,600 vibrations/hour)
Small seconds at 8 o’clock
41 mm diameter, 8.1 mm thick
Transparent sapphire crystal caseback
Slate-colored / silvered opaline, convex external zone
18K white gold hour-markers and “pearl” minute-track
Black Mississippiensis alligator leather with alligator leather inner shell, hand-stitched, saddle-finish, large square scales
Buckle: Platinum 950 buckle, Polished half Maltese cross-shaped
Delivered with a magnifying glass and the resonator of sound “La Musique du Temps” enhancing the sound and the harmony notes of Vacheron Constantin