A monochronomatic palette creates aesthetic harmony
Crafted in platinum for this new model, the 44 mm Duometre case is a contemporary interpretation of the savonette pocket watches created by Jaeger-LeCoultre in the 19th-century. Its rounded contours, amplified by the convex crystal, polished bezel and deeply notched winding crown are highly tactile as well as visually appealing. The apparent simplicity of the case belies its complexity: it comprises 40 separate parts and the lugs are screwed rather than integrated, to enable a mixture of polished, brushed and micro- blasted surfaces that play with shadows and reflections as every movement of the wrist captures the light differently.
Created specifically for this reinterpretation of the Duometre Heliotourbillon Perpetual, the new platinum 950 bracelet combines technical sophistication with refined elegance. Its supple five-row construction ensures exceptional comfort on the wrist, while alternating brushed and polished finishes echo the meticulous finishing of the case. Inspired by the vintage design codes of the Duometre collection, thebracelet’s fluid integration enhances the distinctive rounded silhouette of the case. Each link is individually domed along the 12 o’clock to 6 o’clock axis – subtly recalling the curvature of the lugs – and carefully brushed and bevelled on both sides to create a sophisticated interplay of light.
Harmonising with the cool silvery tones of the platinum case and bracelet, the new all-grey dial is finished in a mix of opaline, brushed and azuré surfaces, creating subtle contrasts between the different indications. The curving platinum bridge that separates the displays from the tourbillon aperture is finished with microblasting and bevelling. In contrast, the polished hands, applied hour markers and frames surrounding the date display create a subtle interplay of light.
Directly expressing the underlying Duometre mechanism, with its two barrels and gear trains, the symmetrical dial layout of the Duometre Heliotourbillon Perpetual forms a triangle, with its apex defined by the grande date display at 3 o’clock. The two power reserves sit above and below the time display. The ‘base’ of the triangle is formed by the display of moon-phases and days in the upper sector, and the perpetual calendar’s months and years in the lower part.
On the left-hand side of the dial, the triple-axis tourbillon performs its ‘spinning top’ rotation and a sapphire crystal window in the side of the case offers another view of its mechanical dance. The tourbillon is set above a background of deep blue lacquer representing a starry sky and, as it spins, red triangles set on the third cage indicate 20-second intervals, which are marked on a sapphire crystal arc.
Breakthroughs in precision: The Heliotourbillon and the Duometre concept
Incorporating Jaeger-LeCoultre’s eight decades of accumulated expertise in the tourbillon regulating mechanism, Calibre 388 features a distinctive tourbillon construction that spins on three axes, enhancing chronometry and creating a kinematic effect that resembles a spinning top.
As it spins on a single axis, the traditional tourbillon does not compensate for the effects of gravity in all positions, which led the Manufacture’s engineers to develop different configurations, including the signature dual-axis Gyrotourbillon. The Heliotourbillon takes this thinking further, with three titanium cages rotating on three axes and a cylindrical hairspring. The first cage is set at a 90-degree angle to the balance wheel and the second cage is set at 90 degrees to the first. Together, these two cages are driven and constrained by an axis tilted at 40 degrees which makes a full rotation in 30 seconds. The third cage is perpendicular to the second and makes a full rotation in 60 seconds. Supported on ceramic ball bearings to minimise friction, the tourbillon consists of 163 components and weighs less than 0.7 grams.
Before Jaeger-LeCoultre developed the Duometre concept, adding complications to a watch movement seemed irreconcilable with accurate timekeeping. That’s because the fundamental requirement of precise timekeeping is that the power supply from the barrel to the escapement should never vary.However, a complication must draw on the power supply to operate, thus interrupting that steady flow and jeopardising precision. Introduced in 2007, the patented Duometre mechanism features two barrels and two separate gear trains housed in a single calibre and linked to a single regulating organ. One gear train powers the time indications and the other drives all additional functions. By separating the power supply in this way, the Duometre mechanism guarantees an exceptionally high degree of operating accuracy.
A perpetual calendar with a grande date display
Complementing the sophistication of the tourbillon and Duometre mechanisms, Jaeger-LeCoultre’s watchmakers integrated a perpetual calendar into Calibre 388. Automatically adjusting for months of different lengths and for leap years, it needs no manual correction until 2100 and subsequently only in centenary years that are not also leap years. The year indication shows the last digit of a leap year in red – a Jaeger-LeCoultre patent. Unusually, in Calibre 388 the hours and minutes can be set either backwards or forwards without compromising the perpetual calendar. Normally, a perpetual calendar is set through the passing of time (the hour and minute hands), so adjusting the time backwards desynchronises and can damage the calendar mechanism. Calibre 388 also includes a Grande Date display: a classical yet rare complication sought-after by watch connoisseurs, and a moon-phase indication accurate to 122 years.
Calibre 388 features fine decoration, even on components that are not visible through the sapphire crystal caseback: brushed surfaces contrast with perlage; edges are hand-bevelled and polished; sunrayed Geneva stripes (côtes de Genève soleillées) radiate seamlessly across the expanse of the bridges. Like all Jaeger-LeCoultre movements, Calibre 388 was conceived, designed, produced, assembled and finished within the Manufacture. Complex, highly innovative and aesthetically refined, the Duometre Heliotourbillon Perpetual in platinum epitomises Jaeger-LeCoultre’s boundless creativity and its technical sophistication represents a new achievement in the Maison’s quest for timekeeping precision.
