Hands-on – Jaeger-LeCoultre Duometre Quantieme Lunaire in white gold and opened dial (live pics, specs & price)

The concept behind the Jaeger-LeCoultre Duomètre has always been highly interesting, from both a technical and visual side. The entire lineup of watches under the Duomètre name are coming with a unique Dual-Wing system, including two barrels and two gear trains. One of the main springs powers the display of the time and the complications, while the other mains spring powers, via the second gear train, the regulating organ of the watch. Both are regulated by a single escapement module, although these two are connected. For the visual pleasure, the movement’s finishing is just superb, like we’re used to from Jaeger-LeCoultre. For the SIHH 2016, a new version of the Jaeger-LeCoultre Duometre Quantieme Lunaire, now in white gold and with opened dial, has been launched, a very good excuse to look back at this watch.

The idea behind the Duomètre concept is simple. All starts from a basic observation. In a traditional complication watch, any function not constantly linked to the gear train makes the watch’s rate deviate upon its activation: a chronograph as it is switched on, a repeater while ringing or even a calendar function that couples just once a day into the running movement – each leads to a drop in the amplitude of the balance wheel, and a deviation in timing, as they absorb power for their own requirements. Even if for some of these complications the effect will only be noticeable after days or weeks – in the case of a chronograph, the effect is immediate, in the case of a date, the effect is lower – it will remain in the end a rate deviation, something that isn’t likable in high-end watches.

The solution found by Jaeger-LeCoultre is the Dual-Wing movement concept, which features two independent power supplies: one is dedicated to creating a precise timing – regulated by the escapement and the balance – and the other solely for the display of time – hour, minute and seconds hands – as well as date and the age of the moon.The Duomètre watches feature actually two independent movements, within one single calibre – but with both gear trains being synchronized through the jumping seconds hand mechanism, thus by the same escapement and balance wheel. This construction ensure that the activation of the complication won’t affect timekeeping and accuracy.

This twin-construction is clearly visible when turning the watch. One barrel is engraved “Heures / Minutes”, this one taking care of the display of the time and the serving the activation of the complications, and the second barrel is engraved “Regulateur”, this second one providing power to the balance wheel and the escapement, to ensure a rather constant supply of power – and providing (on paper) a high chronometric rate. These two barrels provide 50 hours of power reserve to the watch. But on the contrary of other watches with two barrels, these two, in the case of the Jaeger-LeCoultre Duometre Quantieme Lunaire, are not mounted in series and wound simultaneously. Both springs are wound through the crown: rotating it clockwise winds the timing barrel (escapment), turning the crown counter-clockwise winds the power reserve of the functions (hour, minute, seconds, jumping seconds, date, moon phase). This is also why the dial shows 2 separated power reserve indicators.

The movement of the Jaeger-LeCoultre Duometre Quantieme Lunaire, the calibre 381, is like the other watches of the Duomètre concept: a feast for the eyes of amateurs. Build around bridges and plates made in untreated German silver (something that is reserved to high-end watchmaking only), the layout is complex, elegant and deep, offering many layers and recesses to put eyes on. The bridges are adorned with Cotes de Genève Rayonnantes (starting from the center of the balance wheel) and chamfered and polished to a nice glow. Sinks are polished, screws are heat-blued and the main plate has a fine perlage. And don’t change the calibration of your screen, this warm yellowish colour is the actual shade of the movement.

The dial of the Jaeger-LeCoultre Duometre Quantieme Lunaire, with its usual white and grainy (paper-like) finishing, is divided in several areas, giving echo in its architecture to the movement. On the right side sits the traditional timing dial, displaying the hours and minutes. On the left side, we find the aperture for the moon phase and a date by hand around. In the two cut-outs, revealing some mechanical parts of the movement, we have two power reserve indicators, the left one for the “regulateur” and the right one for the indications. Finally, this dial sports an unusual features, as having two second hands.

The first one is classical, and placed in the center of the dial. The other is a jumping second or “Seconde Foudroyante”, displayed in a sub-dial at 6. This hand, which rotates once per second, in 6th of a second increments, besides is captivating ballet, is helpful for adjusting the watch. When pulling the crown, both seconds hands, the center seconds hand and the jumping seconds hand, jump to the zero-position, leaving the escapement running. Pushing the crown back activates both hands simultaneously by re-coupling into the running escapement. The mechanism behind the two hands is based on two escape wheels fixed to the same axis: one works with a lever while the other is driving the seconde foudroyante through a jumping seconds star.

The novelty for this year in this Jaeger-LeCoultre Duometre Quantieme Lunaire is the combination of the smaller case – measuring 40.5mm (while a 42mm edition also existed), in 18k white gold – while it used to be available in 18k pink gold too – white the opened face, and not the traditional plain dial. While being complicated and featuring a massive movement, the Duometre Quantieme Lunaire remains extremely friendly on the wrist. It is an imposing watch, but not because of its case, but more because of a great aura. It is already available in boutiques and retailers and priced at 43.000 Euros.

Specifications of the Jaeger-LeCoultre Duometre Quantième Lunaire 40.5mm White Gold

• Case: 40.5mm diameter x 13.5mm height – 18k white gold – sapphire crystal on front and back – 50m water resistant
• Movement: Calibre Jaeger-LeCoultre 381 – hand-wound – 50h power reserve – 21,600 vibrations/h – hours, minutes and seconds, Foudroyante second, moon-phase indication, date by hand, twin-power-reserve
• Strap: black alligator leather with white gold buckle
• Ref. 6043420 – price: 43.000 Euros.