A Fight for Every Millimeter. The History of Thin Watches: Part Three

In the third part we’re going to tell you about the watches and watch movements that are both highly complicated and thin.

Thin movements and highly complicated watch movements might seem like two completely different worlds. Yet they aren’t worlds apart. The first thing worth mentioning is that the greatest masters of thin watchmaking have had just as much success designing and making seriously complicated watches as they have making thin watch movements.

Moreover, many of them have worked and still work in the same small region — the Vallée de Joux in the Swiss Canton of Vaud. Secondly, it's not an easy task to keep watches from going over a reasonable size when constructing highly complicated mechanical watches.

Take the 44 mm thick Patek Philippe Calibre 89 pocket watch as an example, which was the world's most complicated portable timepiece from 1989 to 2015 with 1728 components in its movement and 33 complications.

The 50.55 mm thick Vacheron Constantin Reference 57260 became the world's most complicated portable timepiece in 2015 with 2826 movement components and 57 complications. The number of complications these models have is of course what determines how thick they are, but these watches would be much thicker if watchmakers didn't make such a great effort to pare each component down and keep the size of functional devices to an acceptable minimum.

In any case, mechanical watches with fewer complications don't present such a serious challenge, because even the addition of another seriously complicated function generally doesn't lead to a dramatic increase in thickness, especially when dealing with pocket watches.

The watchmaker or manufacturer decides whether it is worth investing further resources to slim something down in each specific case, be it the base movement or the additional components needed for a complication, and that's why thin complications have carved out their own separate category.

It was formed at the beginning of the 19th century, when the Swiss watchmaker Abraham-Louis Breguet who worked in France began manufacturing remarkably thin complicated pocket watches, which included one of the earliest examples in this genre: the No. 3306 quarter hour repeater pocket watch made in 1819, which was just 8 mm thick.

A number of inventions and innovations made this possible, including the ruby cylinder escapement that became known as the Breguet ruby cylinder escapement, and the flat wire gongs used by the repeaters. 

Very thin complicated watches were quite the rarity, at least up until the end of the 19th century, when the development of new thin and ultra-thin caliber watches with lever escapements spurred progress in creating thinner complicated watch movements.

Watchmakers working in the Vallée de Joux set the trend for this new art of watchmaking. One factory in particular, that of LeCoultre & Cie, prided itself on designing thin movements in an era when the factory wasn’t in the limelight.

This was due to the fact that it specialized in supplying movements, movement parts and modules to manufactures of finished watches. LeCoultre began designing thin movements at the beginning of the 20th century, and it was around 1920 when the ultra-thin Caliber 18 SMV designed for pocket watches appeared in the factory's arsenal, which was just 3.2 mm thick.

The first half of the 20th century was also when thin perpetual calendar mechanisms and chronograph movements were designed for pocket watches, some of which boasted a split-seconds function. Thin pocket watches with perpetual calendars in 8.5-9 mm cases were presented by the companies Audemars Piguet, Vacheron Constantin, Breguet and Gübelin in the early 1920s.

The race to create thinner complicated mechanical wristwatch movements got off to a start in the 1970s. In 1978, Audemars Piguet presented the first automatic perpetual calendar at the Baselworld watch expo — the Perpetual Calendar Ref. 5548 — which used the ultra-thin Caliber 2120 as a basis for the new movement.

 In total, the Caliber 2120/2800 movement with a perpetual calendar mechanism produced by the Swiss factory Dubois-Dépraz was 3.95 mm thick, housed in a 7 mm thick watch case. These had roughly the same specifications as the first thin automatic perpetual calendar manufactured by Vacheron Constantin, which was unveiled in 1984, the only difference being the leap-year indication, a display which also appeared in perpetual calendars by Audemars Piguet around the same time.

The case of the Vacheron Constantin Patrimony Perpetual Calendar Ref. 43031 was 36 mm in diameter and 7 mm thick. In 1985, Blancpain and Patek Philippe joined the club of manufacturers making thin perpetual calendars. The ultra-thin automatic Caliber 5395 produced at the Frédéric Piguet movement factory was used in the Blancpain Perpetual Calendar Ref. 5395.

It had a perpetual calendar mechanism that didn't factor in the extra day in leap years, and the watch was 8.5 mm thick. It beat the Patek Philippe Perpetual Calendar Ref. 3940 by half a millimeter, which was built on the trademark self-winding Caliber 240 with a micro-rotor. This movement also featuring a perpetual calendar mechanism was 3.75 mm thick, and housed in a watch which was a full 9 mm thick.

In 1985, Blancpain and Patek Philippe joined the club of manufacturers making thin perpetual calendars. The ultra-thin automatic Caliber 5395 produced at the Frédéric Piguet movement factory was used in the Blancpain Perpetual Calendar Ref. 5395. It had a perpetual calendar mechanism that didn't factor in the extra day in leap years, and the watch was 8.5 mm thick.

It beat the Patek Philippe Perpetual Calendar Ref. 3940 by half a millimeter, which was built on the trademark self-winding Caliber 240 with a micro-rotor. This movement also featuring a perpetual calendar mechanism was 3.75 mm thick, and housed in a watch which was a full 9 mm thick.

Breguet entered the game in the 1990s when it unveiled a thin automatic watch with a perpetual calendar — the Perpetual Calendar Ref. 3050. This model equipped with the Caliber 502 QP3 based on the Frédéric Piguet 71 had a case thickness of 7.7 mm.

Only a hand-wound watch managed to squeeze under the 7 mm bar. The case of IWC Schaffhausen's Portofino Perpetuel Calendar Romana Ref.2050 model was 6 mm thick. It used Jaeger-LeCoultre's 1.85 mm Caliber 849 as a base movement, which expanded to 3.15 mm with the addition of a perpetual calendar mechanism constructed by Kurt Klaus.

The Caliber 5621 used in the Villeret Perpetual Calendar Ultra-Slim Lady presented by Blancpain in 2005 was just 2.91 mm thick (based on the 1.73 mm Frédéric Piguet Cal. 21), which made it possible to slim the watch's case down to 6.76 mm. Blancpain declared this watch the thinnest perpetual calendar at the time.

The company that had started the race, Audemars Piguet, was the one that held onto the lead. In 2018, the brand unveiled the RD#2 concept watch with the Caliber 5133, the thinnest automatic perpetual calendar wristwatch at 2.89 mm thick.

In 2019, the brand began using this design as a basis for the serial production of the Royal Oak Selfwinding Perpetual Calendar Ultra-Thin model — the world's thinnest automatic perpetual calendar with a 6.3 mm thick case.

This was also the first brand to begin designing ultra-thin tourbillon wristwatches. The year 1986 was not only the year when Audemars Piguet presented the Tourbillon Ref. 25643, there were another two world firsts. It was also the year when the company produced the first series of tourbillon wristwatches, and the year when the first self-winding tourbillon debuted.

The watch’s alternative construction with the caseback serving as the main plate for the movement made it possible to slim the watch down to 4.8 mm, an unbelievable measurement, and it was not long before this record was broken. In 1989, Blancpain arrived on the thin tourbillon scene with the hand-wound JB 1735 Tourbillon Ref. 0023. The watchmakers at Blancpain didn't even come close to Audemars Piguet's record.

The watch's Caliber 23 movement was 3.5 mm thick and the watch was 8 mm thick. However, they did create their own niche category, as their Caliber 23 from the Frédéric Piguet movement factory had an impressive eight-day power reserve. Piaget also managed to create a 3.5 mm movement — the Caliber 600P — a hand-wound tourbillon movement designed and launched for production in 2002.

Breguet, whose founder is credited with the invention of the tourbillon, designed what was the thinnest automatic movement with a peripheral rotor when it was unveiled in 2013, and this 3 mm thick movement was housed in the 7mm thick Tourbillon Ref. 5377. Bvlgari was the company that made the most progress, which presented the world's thinnest hand-wound tourbillon movement in 2014.

At 1.95 mm, the BVL 266 caliber was the same width as the automatic BVL 288 caliber presented in 2018 with a tourbillon and peripheral rotor. Bvlgari's Octo Finissimo Tourbillon watch created based on the BVL 288 remains the thinnest tourbillon, with a case thickness of 3.95 mm.