Hands-On With the New Jaeger-LeCoultre Duomètre Collection

Looking back at Watches & Wonders 2024, it seems clear that one of the most impressive showings came from none other than Jaeger-LeCoultre. The brand brought some welcome updates to its Duomètre collection, including an entirely new Heliotourbillon fit within a Duomètre Perpetual Calendar, the latest in JLC’s series of multi-axis tourbillon creations. The Duomètre is an often misunderstood horological powerhouse, and Jaeger-LeCoultre has breathed new life into the collection by returning to its roots. Going hands-on with the new Duomètre watches at this year’s show left an indelible impression, and it’s one of the few watches that lingers in my mind months later.

The Duomètre was first released in 2007, making it a relatively modern advent, though the inspiration dates to the late 19th century and the pocket-watch caliber 19/20RMSMI. The idea is relatively straightforward, acknowledging that complications additional to timekeeping will compromise the precision of a watch’s core function. This is because complications, such as a chronograph or any calendar elements, tap into the same energy source, gear train, and regulation system employed by the hour and minute hands. Therefore, Jaeger-LeCoultre created a movement that split the timekeeping aspects from any complications by providing each their own source of power and gearing — meaning that each could function independently of one another, while linked to a single escapement.

That last part may sound a bit odd, but the manner in which these two gear trains are linked within the Chronograph is rather interesting. The escape wheel features two levels, one acting on the palette fork as you’d expect, and the other a foudroyante star, effectively linking both going trains to the balance wheel. The foudroyante seconds hand, when timing is activated,  makes a complete rotation of its subdial in one second, stopping (very) briefly six times along the route. This allows for an incredibly dynamic view of the complication at work, and doesn’t sap any of the energy flowing through the gear train displaying the time. 

The collection made its debut with a chronograph, and the Caliber 380, and this year, Jaeger-LeCoutlre returns to that formula with the Duomètre Chronograph Moon and the Duomètre Quantième Lunaire. As their names suggest, both of these watches display the phases of the moon, but the former dials things up to 11 while the latter keeps the presentation as simple as possible. Both are equally compelling examples of an updated formula, but the Duomètre Chronograph Moon is the star of the show among these releases (excluding the Duomètre Heliotourbillon Perpetual, which we’ll get to in a moment). 

The Duomètre Chronograph Moon is a modern, thoroughly mature take on the design language that Jaeger-LeCoultre developed around this collection. This timepiece makes use of a new caliber, the 391, which can now be viewed through open sections of the dial, underneath the dual power-reserve indications (one for each mainspring). This execution initially felt like an unnecessary step for what is a somewhat demure watch (this is a sleeper-style watch if there ever was one), but upon reflection, it makes a good amount of sense from a storytelling perspective. 

The two apertures provide a view to the two ends of their respective gear trains, one following the timekeeping’s trail to the escapement, the other revealing the chronograph works leading up to the foudroyante at the bottom of the dial. Each window hints at the conceptual nature of the watch, leading to a natural meeting point. It also allows the watch to boast some of its exceptional finishing without having to be flipped over. I’m generally not all that keen on openworked dials, but this Duomètre offers a nice balance that doesn't compromise the legibility of the core functions set within two large subdials above the centerline. It’s a symmetry that works, and helps drive the point home that there’s indeed something special going on under the hood here. 

That said, this is indeed a watch that you’ll want to flip over. The Caliber 391 at work gets a stunning finish that radiates from the balance wheel toward the bottom. The striping widens toward the top of the movement, connecting with the two mainspring barrels that can be wound manually in either direction. As you might expect, there is plenty of depth to this movement, drawing the viewer in for a closer look to discover the layers of gears, bridges, and plates. It sounds clichéd, but it really must be seen in person to be fully appreciated. 

The Duomètre Chronograph Moon places the moon-phase display within the totalizer subdial on the right, and introduces a day/night indication nested within the hour-and-minute subdial on the left. The Duomètre Quantième Lunaire features a fully closed dial, and keeps just the moon-phase display nested within the hour and minute subdial, which is situated at the right side of the dial. Unlike the Chronograph Moon, the Quantième Lunaire is available in a steel case, and its price reflects that (none of these are inexpensive, mind you). As visually and mechanically impressive as the Chronograph Moon is, the Quantième Lunaire feels like the better daily option of these releases. Well, as “daily-wear” as a watch like this can be, I suppose. It also feels like the more “old-school” option visually, which I quite enjoy. 

The design of the dial and case are new, though heavily referential to the original Duomètre references. The case of each measures 42.5mm, while the Lunair measures 13mm in thickness, and the Moon measures 14.2mm in thickness. The Moon is available only in precious metal options, including pink gold, and platinum, while the Lunaire is only available in steel — another mark in the “daily” column for the Lunair. 

All three of these watches are immensely impressive in the hand and on the wrist, and only become more so the deeper you dig in and understand them. If there is such a thing as a “watch nerd’s watch,” it is surely theDuomètre, and the latest execution brings the concept firmly into 2024. It’s worth noting that Jaeger-LeCoultre has made a broad range of Duomètre references since 2007, many of which can be found in the secondary market at what I would call reasonable prices considering their complexity and pedigree. 

Finally, the flagship release within the Duomètre collection this year was the Heliotourbillon Perpetual. This is a new tourbillon architecture from Jaeger-LeCoultre, and represents the first one built around a triple axis. The model follows the other multi-axis tourbillons we’ve seen from the brand, such as the Gyrotourbillon and the Sphérotourbillon, and like those examples, it offers one of the more dynamic takes on the tourbillon that you’re likely to come across. The Duomètre Heliotourbillon Perpetual is, well, a perpetual calendar, which is the other complication making use of the second mainspring and gear train. But with the regulating organ residing in a spinning cage, it makes the connection point between the two elements a bit tricky. 

The tourbillon itself consists of 163 components, and weighs just 0.7 grams thanks to the use of titanium. The first of its cages is set at a 90-degree angle to the balance wheel, while the second is set to a 90-degree angle from the first. Together, they are tilted at 40 degrees, and make a full rotation each 30 seconds. The final cage is perpendicular to the second, and rotates at half speed, making a full rotation in 60 seconds. It looks exactly as impressive as it sounds in action. A cylindrical hairspring occupies much of the internal space. The base of the tourbillon sits within the movement plate, receiving power from both mainspring barrels, and it is here that a small click-shaped gear engages to link power to the calendar complication. 

This is a full perpetual calendar display, meaning you’ll get the day of the week, date (in large format at 3 o’clock), month, and year. There’s even a moon-phase indication thrown in for good measure. What I love about this perpetual calendar is how Jaeger-LeCoultre has chosen to integrate the leap-year indication within the year window. The maison has patented a way to display the final number of the year in red only on leap years, meaning the use of multiple disks must be orchestrated behind the scenes. It’s an elegant solution, and a bit mysterious at that. 

Just 20 pieces of the Duomètre Heliotourbillon Perpetual will be produced over the span of a year, and you can expect additional case metal and dial color options in the future to carry this concept forward. This is such a fun watch to get lost in, and at every corner you’ll find something new to dive into. It’s difficult to imagine wearing a watch like this with any frequency, but it’s a watch that reminds you of the kid-like wonder that can pull you into this hobby, and why we get so passionate about an “obsolete” technology in the first place. This timepiece transcends all that, and just like the Duomètre Chronograph Moon and Lunair, will surely put a smile on your face.