Could this be the thinnest mechanical watch in the world? Jaeger-LeCoultre Master Ultra-Thin Squelette (specs & price)

This article wasn’t supposed to start like that. We thought we would be in front of a new iteration of an ultra-thin Jaeger-LeCoultre – a nice one for sure but different just because it was featuring a skeletonized movement. Thus, our article would have been turning around describing you the nicely opened and engraved bridges and the enameling work done on the dial. However we, at Monochrome-Watches, like to be precise – and them came the surprise. This Jaeger-LeCoultre Master Ultra-Thin Squelette is said to be 3.6mm height, making it possibly the thinnest mechanical watch in the world. We had to investigate!

Basically, this new Jaeger-LeCoultre Master Ultra-Thin Squelette is the openworked and enameled edition of a very subtle and elegant watch that we reviewed a few months ago, the Master Ultra-Thin 1907, a timepiece that our editor-in-chief praised for its understated presence, its overall comfort and of course, for the technical achievement it represents. At the time of its introduction, it was the thinnest mechanical watch in the world – with a case measuring only 4.05mm and a movement of 1.85mm height. Even if Piaget achieved to launch in 2014 a mechanical watch measuring 3.65mm (the Altiplano 900p), the watch created by Jaeger remains a superb technical prowess. However, (and that’s a big HOWEVER), we had kind of a surprise when reading the press release about the Jaeger-LeCoultre Master Ultra-Thin Squelette and looking at the dedicated page on the website (here). Jaeger stands a total height of 3.6mm – yes, 3.6mm ONLY! If we’re right, it would mean that this new Jaeger-LeCoultre is the thinnest mechanical watch in the world – and that they achieved to do that with a skeletonized movement and a see-through caseback.

Considering the importance of such numbers, we decided to directly ask the manufacture, which kindly answered our question by a simple “The watch is indeed 3.6 mm thick” together with this document attached:

What you can see here is the comparison between the actual Master Ultra-Thin 1907 and the two new skeletonized editions of the Master Ultra-thin (set or non-set). The statement is clear: the watch is indeed measuring 3.6mm – so yes, the Jaeger-LeCoultre Master Ultra-Thin Squelette is the actual thinnest mechanical watch from the entire industry – and Jaeger-LeCoultre achieved to do that with a very classical construction (in the Piaget, the caseback is actually the main-plate of the movement, thus reducing the height of the entire watch). Here, we have a bezel with a crystal, hands, a movement and a sapphire caseback… Of course there’s no dial BUT there’s a skeletonized movement – that usually is thicker than a normal movement. Here the Calibre 849SQ measures the exact same 1.85mm as the Calibre 849 (non-skeletonized). Considering the absence of dial, you know now where the difference is. The worst is that Jaeger-LeCoultre is not even communicating about it. Sorry, but we think it’s BIG. What an achievement!

Back to the watch itself. The movement is opened in the traditional way, with hollowed bridges and ribs engraved with classical arabesque pattern. This impressive finish can be admired from both the dial-side and the caseback. The Calibre 849SQ has the exact same dimensions and nearly the same specifications as the non-skeleton edition, meaning that it measures 1.85mm, it features 119 parts and 19 jewels (vs. 123 parts and 19 jewels on the non-skeletonized one) and it boasts 33-hour of power reserve (vs. 35h for the non-skeletonized one). Of course, this is a short power-reserve but the diameter and the thickness of the movement are so unique that we totally excuse Jaeger for that.

What surprises most is the size of the movement – something that we couldn’t really imagine with the Master Ultra-Thin 1907 as the caseback was full. Here, the movement is clearly floating in the small 38mm case. However, Jaeger-LeCoultre cleverly hides this impression with an enamel circle around the engine that creates an hour ring, with 12 zones. Depending on the material of the case (18k rose gold or 18k white gold), this enameled ring comes in a rich chestnut brown or a deep blue.

Each edition of the Jaeger-LeCoultre Master Ultra-Thin Squelette will be available in a limited edition of 100 pieces, priced at 56.000 Euros in Rose gold and 58.500 Euros in white gold. Now, the only thing to do is to compare this JLC with the Piaget Altiplano 900P in the flesh, with precision instruments, in order to be sure of who really have the thinnest mechanical watch in the world. From now, Jaeger-LeCoultre wins the game! Bravo! More details here and here.