Hold the press : this is not a Summer Special in a woman's magazine. Watches do not need to go on a diet. They choose to do so because they're chasing glory, technical feats and above all else, for the kick of it.
Going slimmer than 6 mm is far from a necessity for a watch. But as the informal limit of ultra-thin timepieces, it also marks the spot where things start becoming really more difficult. Margins for error and tolerances are challenged in a unique way, much like when entering the 5000-meter zone. In watchmaking as in mountain-climbing, you want to go for the summit. The thing is, if maximum altitudes are set by the reality of geology, watchmaking records keep being pushed.
Between 2020 and 2022, three timepieces have gone after the record of world's thinnest ever, and each one has driven the limit further down. The first one is the Altiplano Ultimate by Piaget : 2 mm thick. Then Bulgari launched its Octo Finissimo Ultra : 1.80 mm. Both of them have received an award at the Grand Prix d'Horlogerie de Genève. And finally, Richard Mille put a (temporary?) end to the debate with the 1.75 mm-thick RM UP-01 Ferrari. Now we're done with the podium, let's look at the forces at play here.
To establish the credibility and importance of their exploits, these brands have put forward the extreme difficulty they've encountered. They've set foot in a zone where the physical integrity of their watches is being challenged on a daily basis by things as trivial as temperature variations, being worn on a wrist, and time. In a 2-mm timepiece, several components are slimmer than a 10th of a millimeter. That's as thin as your average aluminum foil. And I'm only talking about simple components, with a simple geometry and your basic constraints. Now imagine what happens to a barrel, with a 7 foot-long spring pushing inside...
More importantly, these three have positioned themselves on either side of a philosophical line. When going beyond the 3-mm threshold, you have to shave absolutely everything you can. And there's a very simple, smart and longstanding solution to do that. Instead of assembling a caseback, a movement and a crystal held by a bezel, you just scrap one of these three layers. Flat on the outside, the inside of the caseback can be machined to present the same relief and function as the movement's mainplate. This construction, known as two-in-one, has helped the Swatch become simpler and therefore, cheaper. Piaget and Bulgari have adopted it, although for other reasons.
This seems so clever and efficient a way to go about the manufacturing of a slim watch that when Richard Mille did away with it, it made the shock of their release even bigger. Even though they had zero experience in making slim timepieces, they blew three assumptions to smithereens. One is the construction itself, as the RM-UP1 has a two-part case and a movement, which is 1.18 mm thick, and these are separate entities. The second is the shape one naturally expects from a watch. The RM-UP1 is neither round nor rectangular nor square nor coussin nor tonneau nor anything known thus far. Its frame is entirely defined by its content, and said content is in turn governed by the shape of the movement's organs. For example, since they didn't have enough thickness for a crown, they decided to pluck two holes in the mid-section of the case, which look just like the ones on a vintage audio cassette.
The third assumption they got rid of is of a sales nature. Piaget first introduced the Altiplano Ultimate as an experimental piece. It took them another two years to make it into a commercial product, which is manufactured solely on request. Bulgari edited theirs in a 10-piece limited series. They estimated it was the maximum number of people that would be willing to spend 400 000 CHF on a titanium, no-complication timepiece. Richard Mille has announced 150 pieces, sold 2 million CHF a pop. Which goes to prove that watchmaking has no limits, neither physical nor logical nor technical. Those keep being pushed back every time one thinks that, this time around, for sure, they're set in stone.
