News: Introducing the Vacheron Constantin Patrimony Ultra-Thin Calibre 1731. The Thinnest Minute Repeater in the World, Now in Two New Platinum-Clad Versions.

Here we have another two new pieces also just unveiled at 2015 Watches & Wonders in Hong Kong. The new Vacheron Constantin Patrimony Ultra-Thin Calibre 1731 is the thinnest manual wound calibre and the thinnest manual 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 now appears clothed in a platinum case —framing a silvered opaline or slate-colored opaline dial— naturally bearing the prestigious Hallmark of Geneva. The first repeater watch appeared in the 18th century in an age before the advent of electric lighting. The timepiece enabled its owner to tell the time in the dark by means of an audible indication. While this complication is no longer an imperious necessity, it nonetheless remains a pinnacle of the watchmaking art. Each minute repeater watch is indeed unique and carries the signature of the master artisan who made it. Each lives its own life and plays its own music, providing a unique space for fleeting moments of grace and deep-felt emotions when its chimes ring out. On demand, the minute repeater strikes the hours, quarter-hours and minutes.

Activating the dedicated slide piece —the only element of this major complication visible on the dial side— causes a hammer to strike a low-pitched gong to mark the hours, while the quarters are played by two hammers on two gongs —one low-pitched and the other high-pitched— and the minutes are sounded on the high-pitched gong.

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 Calibre 1755, a minute repeater movement just 3.28 mm thick: an unprecedented feat! 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 than its predecessor from 1992 —due to an impressive 65-hour power reserve—, measuring a mere 3.90 mm compared with the original 3.28 mm. However, 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 stabilize 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 instills 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 spectacularly 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 re-entrant angles, such as can notably be found on the seven bridges of Calibre 1731.

The Patrimony ultra-thin calibre 1731 conceals remarkable complexity beneath its apparent simplicity. Its design 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 manual wound watch at 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 recognizable.

Platinum was a precious metal long reserved for royalty and maharajahs. It continues to convey a definite sense of prestige that is recognized by a distinguished elite of connoisseurs and collectors. Used since 1820 by the watchmakers of the Maison, platinum has been used for a number of creations, ranging from the complex to the most original. Its 95% precious metal composition render it far purer than gold at ‘just’ 75%. This is not however what sets platinum apart from the other precious metals: its rarity, its density and its weight make it a material that is not only prestigious, but also far superior in terms of durability, resistance and malleability.

These qualities mean that a small scratch on a platinum model merely displaces the metal and thus engenders minimal loss. A platinum watch thereby maintains its value, as befits a token of eternity. Resistant to oxidation and the passing of time, this inalterable metal is synonymous with continuity and ensure its role as a perfect and enduring lifelong companion. Such a prestigious complication as the minute repeater, cloaked in the most precious of all materials, combine to this a supremely complicated model capable of appealing to the most discerning connoisseurs and collectors.

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Technical Specifications

Patrimony ultra-thin calibre 1731 References 30110/000P-9999 and 30110/000P-B089.

Movement: Manual wound Calibre 1731 fully 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)
265 components
36 jewels
Indications Hours, minutes
Small seconds at 8 o’clcok
Minute repeater

Case: Platinum 950 with 41 mm diameter, 8.1 mm thickness and not water-resistant.

Dial: Slate-colored or silvered opaline, convex external zone with 18K white gold hour-markers and "pearl" minute-track.

Strap: Black Mississippiensis alligator leather with alligator leather inner shell, hand-stitched, saddle-finish, large square scales and fitted with Platinum 950 polished half Maltese cross-shaped buckle.

Other Specs: Accessories delivered with a magnifying glass and the resonator of sound "La Musique du Temps" enhancing the sound and the harmony notes of Vacheron Constantin.