In 2013, Arnold & Son raised eyebrows with their Ultra-thin Tourbillon Escapement “UTTE” watch which, back then, was the world’s thinnest tourbillon watch. The watch was just 8.34mm thick and housed the calibre A&S8200 which measures just 2.97mm thick. Though it has since lost the title of thinnest tourbillon watch to the Bulgari Octo Finissimo Tourbillon (hands-on here), the UTTE still remains an impressive masterpiece.

Skeletonizing a watch is no easy feat. And it’s doubly hard for an ultra-thin movement, mainly because the movement is already so thin that removing any more material is bound to affect structural rigidity. As a result, the A&S8200 calibre in the Arnold & Son UTTE Skeleton watch had to be thoroughly redesigned and re-engineered. The result is the A&S8220 calibre, which measures 3.3mm thick. The extra thickness, according to Arnold & Son, is necessary to guarantee rigidity as they sought to skeletonized the movement. Still, let’s face it, 3.3mm for a tourbillon movement with two barrels and a power reserve of at least 90 hours is seriously impressive.

The new A&S8220 calibre boasts some major revisions. For instance, the main plate has been heavily modified to reveal as much as possible of the inner workings. But perhaps what’s most visible to owners is that the tourbillon cage has been totally reworked to show off more of the mechanism while retaining the three-dimensional design that has become a signature of the earlier Arnold & Son UTTE watch. In addition, the tourbillon cage is relatively large as compared to the movement. It measures 14mm across, while the movement itself is 32mm. This means it’s the single most dominating component of the dial, and on top of that is the fact that the cage is fully hand-polished and chamfered, making it a real visual treat for owners.

This is possible because they are a part of the Swiss watch movement manufacturer La Joux-Perret (yes, it is possessed by the Citizen Group out of Japan – however they do not actually make any decisions about how it’s run, to be honest), which gives Arnold & Son the capacity to do things most of its rivals simply can’t. At least not with this scale. What’s really driving the innovation forward is likely Sebastien, who just has a lot of ideas to stay idle.Ignore the movement and dial, along with the Arnold & Son Nebula is quite much what we’ve come to expect out of Arnold & Son dress-style watches. The Arnold & Son Nebula comes from either steel or 18k red gold, and the circumstance is 41.5mm broad and 8.73mm thick – which makes it incredibly wearable. It isn’t the smallest or the largest dress watch that Arnold & Son makes, but using its thinner instance along with classical proportions it surely works well as a more formal timepiece.In images, the three-dimensional thickness of the dial is not easy to convey. For me, that’s really the magic of looking into the Arnold & Son Nebula – in addition to the visually very attractive symmetry of the motion structure. Arnold & Son isn’t likely to beat Patek Philippe, Chopard, or Vacheron Constantin nowadays in regards to the degree of motion finishing, but it is pretty good – especially for the money. More to the point, over the years I have actually seen it get better – for example, in how they do the beveled edges on the ends of movement bridges or wheels.

And as you would expect, the A&S8220 calibre is also treated to the finest haute horlogerie finishing: The main plate and bridges are constructed using nickel silver and finished with Côtes de Genève rayonnantes; The edges are also polished and chamfered; The steel components, gears, and ratchets are all satin-finished with their edges polished and chamfered; The screws have bevelled and polished heads, and finally, the jewels are placed in polished countersinks; Reading of the time is done off a sapphire disc with printed numerals at 12 o’clock; The hour and minute hands are golden and feature white lacquered tips.

The Arnold & Son UTTE Skeleton comes in a 42mm 5N red gold case, which is as exquisitely crafted as the movement. It is stepped, tapering from top to bottom. The dial part, which is the widest section, also features an extra-large sapphire glass to showcase the caliber A&S8220 in all its glory. The bottom of the case is made narrower to fit snugly on the wrist.

The Arnold & Son UTTE Skeleton watch will be limited to just 50 pieces, and each watch will come with a hand-stitched brown or black alligator leather strap with a matching 5N red gold buckle with the Arnold & Son logo. Price is $76,750. arnoldandson.com