Review: The New Jaeger-LeCoultre Duometre Quantieme Lunaire in Stainless Steel

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In 2007, the world welcomed the Duometre, an innovative and original timepiece by Jaeger-LeCoultre that aims to solve the age-old conundrum of accuracy in complicated mechanical watches. At its core, the Duometre mechanism features two barrels and two independent gear trains: one for timekeeping and one for complications – linked to a single escapement. By separating the power supply in this way, the balance is free from the influences of power fluctuations caused by the running of complications; in theory, the steadier flow of power to the balance optimises operating accuracy. The Duometre was placed on the backburner for a bit in recent years for Jaeger-LeCoultre to focus on other collections like the Reverso or the Master – well, that was until this year.

Jaeger-LeCoultre Duometre Quantieme Lunaire in Stainless Steel

In 2024, the brand is championing the Duometre collection once again with the introduction of two new models: the Chronograph Moon and the Heliotourbillon Perpetual. But there is also a third Duometre that made its debut at Watches & Wonders earlier this year – the Quantieme Lunaire in stainless steel. Releases like this are usually a non-event because ‘it’s an old model’. But the Quantieme Lunaire remains one of the most popular Duometre models ever, and it is now available in non-precious metal for the very first time. It is also fitted with an updated case and never-before-seen dial aesthetics. Here, we bring you the details and our honest thoughts on Jaeger-LeCoultre’s latest, next-gen Duometre Quantieme Lunaire.

The Case, Dial and Hands

The case of the new Jaeger-LeCoultre Duometre Quantieme Lunaire measures 42.5 mm x 13.05 mm, which is 0.5 to 2.0 mm larger than its predecessors, depending on the reference. For the first time for this model, the case is made of stainless steel, a boon for those who find precious metals too flashy, dressy or pricey. But wait, there’s more – the case has now also been redesigned and is nearly unrecognisable compared to the old version. While the old design was clean and austere, it was a cookie cutter design and wasn’t very exciting. The new case design for the Duometre’s next generation has got a neo-vintage thing going for it and exudes flair. Inspired by savonette pocket watches created by the Maison in the 19th century, the case is fitted with domed sapphire crystal at the front and back. Combined with a curved bezel, they give the case a smooth, curvaceous profile that resemble a bar of soap (hence savonette). The lugs are now screw-in rather than integrated, which gives the manufacturer’s finisseurs better access to nooks and crannies. Indeed, the finishing on the case, like its new design, is more nuanced than ever before, with a harmonious mix of polished, brushed and micro-blasted surfaces. Even the crown has been thoughtfully redesigned to complement the new case, now featuring deep, rounded notches for better grip and added character.

The new Duometre case is one of Jaeger-LeCoultre’s most nuanced. Where it loses in elegance (relative to its predecessor), it gains in flair.

While there have been wholesale changes applied to the case, the dial remains relatively unchanged. The iconic three-counter layout is still there: time at 2 o’clock, date and moon phase at 10 o’clock, and foudroyante at 6 o’clock. On both flanks of the foudroyante sub-dial are power reserve displays – one for each barrel. And as before, the absurdly long central running seconds hand dominates the visage of the new Duometre Quantieme Lunaire. What’s different this time is largely cosmetic. The Duometre Quantieme Lunaire finally gets a blue dial, something that – surprisingly – has evaded the collection all these years. The sectorised dial is finished in a variety of styles: opaline (main dial, power reserve arc), sunray (center of counters, power reserves), and circular blue (around counters).

The dial design remains largely unchanged as there’s no need to fix what already works.

The Movement: JLC Caliber 381

In the midst of change, one key element stays virtually the same: the 374-part, 40-jewel Calibre 381, used in every Quantieme Lunaire reference since inception. The movement has a power reserve of 50 hours and operates at a stately 3 Hz frequency. They key differential between the Calibre 381 and most other watch movements is the Duometre mechanism, which is all about integrating ‘two independent movements’ under the same hood to optimise timekeeping.

The Calibre 381 as seen through the sapphire crystal case back.

What this really means is that each of the two mainspring barrels inside the Calibre 381 is dedicated to driving either just the timekeeping or the complications. The calibre is still regulated by the one balance and escapement, but the separation of power source produces two benefits for timekeeping: 1) it ensures that the operation of complications does not affect power flow to the regulating organ, and 2) having one barrel focused only on timekeeping ensures a more constant supply of energy and thus – at least on paper – better chronometry. The benefits become more pronounced come midnight when the date and moon phase mechanisms switch over; even temporary fluctuations in energy demand can perturb chronometry. To allow the mainspring barrels to function independently, they have not been mounted in series. As such, turning the crown as per usual will not wind both barrels at once. To wind the barrel responsible for timing, the crown must be turned clockwise, while turning the crown counter-clockwise winds the other barrel that’s responsible for complications.

Among the functions of the JLC Calibre 381 are the time in hours, minutes and seconds; the date; the moon phase; and the foudroyante. The foudroyante is capable of displaying the passing of time in 1/6th of a second intervals; the foudroyante hand makes a full rotation every second. Why 1/6th of a second? Because the balance wheel in the Calibre 381 makes 6 semi-oscillations a second (3 Hz), or 6 ticks per second. Though not exactly the most pragmatic of complications, the foudroyante never fails to captivate beholders with its mesmerising dance. With the Calibre 381’s zero-reset function, pulling the crown out stops and re-zeroes both the centre second and foudroyante hands. This allows time-setting to be performed with utmost accuracy.

The Calibre 381 is finished to a superlative level, similar to that of the brand’s more premium offerings. The numerous bridges seen through the sapphire crystal case back are decorated one-by-one with sunrayed Geneva stripes. These stripes line up perfectly from bridge to bridge as they appear to emanate from the balance as the centre. The edges of these bridges are beveled and polished to a sheen.

The Competitive Landscape

The JLC Duometre Quantieme Lunaire is more than just a wristwatch with a pretty moon phase. In fact, it is fairly unique, with its independent power sources and gear trains, and the inclusion of a foudroyante. At USD44,300 a pop for the Duometre Quantieme Lunaire in stainless steel, “a little overpriced” is what comes to mind initially, given that the gold variants of the same model from just four years ago were available at a lower price. However, upon deeper consideration, you’ll find that this is what years of price adjustments does. It didn’t help that inflation was accelerated in previous years as well. It is unfortunate that one has to pay the price of a gold Duometre for a steel one, but that’s just how the market is these days.

The new Duometre Quantieme Lunaire wears larger than its predecessors, despite being the same model.

A worthy alternative to the JLC Duometre Quantieme Lunaire has to be one of A. Lange & Söhne’s Lange 1 moon phase watches, specifically the Lange 1 Moon Phase or Grand Lange 1 Moon Phase. While they lack the Duometre’s independent gearing and foudroyante, other aspects of the watch are similar: off-centre sub-dials; power reserve, date and moon phase functions; and a manually wound movement. The Lange 1s do, however, have superior finissage, which also translates to a more premium pricing. It comes down to what one’s preference is: superlative craftsmanship or innovative watchmaking.

The new Grande Lange 1 Moonphase on the right and the now discontinued Lange 1 Moonphase.
The Lange 1 Moon Phase (left) and Grand Lange 1 Moon Phase (right) – both in pink gold.

For something a little more classical, look no further than the Vacheron Constantin Patrimony Moon Phase Retrograde Date. It literally is just a moon phase watch with a retrograde date as its most fancy function. At 42.5 mm x 9.7 mm, it is just as big as the Duometre Quantieme Lunaire but significantly thinner. Out of the three timepieces here, the Patrimony unsurprisingly has the cleanest dial, and sits somewhere in between the Lange and the Jaeger-LeCoultre with respect to level of finissage. With the standard issue gold model priced at EUR54,000, it is clearly more expensive than the steel Duometre Quantieme Lunaire. Once again, it is a matter of what one values in a watch, form or function?

The Vacheron Constantin Patrimony Moon Phase Retrograde Date – Collection Excellence Platine.

Concluding Thoughts

The longevity of the Jaeger-LeCoultre Duometre Quantieme Lunaire is testament to its commercial and watchmaking success. Visually appealing and technically fascinating, it now gains a second wind as it receives a welcomed case and dial update. The fact that the model is now available in stainless steel can only be a plus for collectors as the Quantieme Lunaire attempts to maintain a sliver of the value proposition that it once prides.


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