For me, the Lemania 2310 or CH 27 — as was its name while in development by the brilliant Albert Gustave Piguet, the movement maker’s technical director — is the most beautiful, historically significant, and yes… the greatest chronograph movement of all time. And yes, I’ve taken into consideration the sublime Victorin Piguet ébauche movements from the 1920s, the Longines calibre 13.33Z and even the Valjoux 13-130.

There are three things that are particularly extraordinary about the 2310. The first is the great technical leap forward it represented in 1942, when it was first launched. At 27mm in diameter and 6.74mm in height, it was the world’s smallest chronograph movement then, beating both the 13.33Z and 13-130, which were both 13 lignes (29mm), by a considerable margin. (As an aside, if you’ve ever wondered why a Patek reference 130 has its sub-dials pushed all the way to the edge of its 33mm case, it is because of the size of the Valjoux movement within.) Being a smaller-sized movement made the 2310 incredibly adaptable to different case styles and configurations.

The second thing is that, from 1946 to 1968, it was used by Omega as the calibre 321, where it had an unrivalled track record for incredible reliability and performance, culminating in it powering the only watches that passed NASA’s torture test for certification for use in space.

Open caseback on a 1950s Lemania Chronograph in rose gold, showcasing a Lemania 2310 chronograph movement (Image: ninanet.net; SteveG’s Watch Launchpad)

The Lemania 2310 is immediately recognizable with its durable and adaptable architecture; the movement uses a column wheel control system; levers and springs were cut and shaped from a thick steel sheet; bridges here are plated with pink gold; finishing on the movement is highly functional (Image: ninanet.net; SteveG’s Watch Launchpad)

The column wheel control system used for the Lemania 2310 (Image: ninanet.net; SteveG’s Watch Launchpad)

An example of the Omega Speedmaster ref. ST105.012, which was powered by the Calibre 321, Omega’s own take on the Lemania 2310; the movement was used to power the Speedmaster from 1959 to 1968, when it was replaced by the Calibre 861; the ST105.012 and ST145.012 were the Speedmasters that went to the moon on the wrists of Apollo astronauts (©Revolution)

The third: as it was really the only manual-wind, column-wheel, classic chronograph being manufactured in ébauche form in the ’80s, it played a seminal role in the Swiss watch industry’s recovery from the Quartz Crisis, allowing maisons such as Patek Philippe, Breguet, Vacheron Constantin and Roger Dubuis to collectively stage the resurgence of the mechanical chronograph. Two of these brands, Patek Philippe and Breguet, even built split-seconds versions of this movement — a considerable technical undertaking as explained to me by the legendary Philippe Stern.

The thing to understand is that without Omega, the calibre 2310 would never have been born. By the beginning of the 20th century, Omega had become synonymous with the chronograph complication. Indeed, it had launched its first pocket-watch chronograph movement, the 19‴ CHRO, a full century before in 1898. This was followed up by the 18‴ CHRO in 1906 which was also a pocket-watch movement, though it was famously adapted for use in the world’s first wristwatch chronograph. Both the 18‴ and 19‴ CHRO were of the monopusher configuration with stop, start and reset all activated by a single pusher. Omega then created a movement called the 39 CHRO which was made between 1929 and 1940. It was still largely used in pocket watches, but occasionally in wristwatches and in monopusher and bi-pusher configuration. Then, something happened called The Great Depression.

The 18’’’ CHRO caliber as it would’ve looked when it was pulled out from the vaults of Omega’s Museum

A multi-scale Omega monopusher chronograph pocketwatch ref. 1067 from the 1940s, powered by the Calibre 39 CHRO (Image: bruun-rasmussen.dk)

The Calibre 39 CHRO powering the above multi-scale Omega monopusher chronograph pocketwatch ref. 1067(Image: bruun-rasmussen.dk)

The Workhorse Chronograph

The Great Depression, which began in 1929 and endured for a decade, was the result of artificially inflated stock prices. Everyone rode the stock market’s bull rush throughout the heady, lascivious Jazz Age of the 1920s, forging an eerily accurate precursor to the events that led to the subprime mortgage crisis almost 90 years later. Stock prices boomed even as consumer debt spiralled out of control, unemployment rose and the agricultural sector failed due to droughts. Finally, there was a total global loss of confidence in the stock market, and a financial and economic bloodbath ensued. As you can imagine, the demand for mechanical watches was severely impacted. But it is incredible that with every global crisis — the Great Depression, the Second World War, the Quartz Crisis — the best watch brands reacted with creativity and courage.

Migrant Mother by Dorothea Lange — A poverty-stricken migrant mother (Florence Owens Thompson, 32) with three young children gazes off into the distance. This photograph, commissioned by the FSA, came to symbolize the Great Depression for many Americans (Getty Images)

Strength in consolidation became a key strategy, and with that, Omega, Tissot and Lemania joined forces between 1930 and 1932 in a new group was called the Société Suisse pour l’Industrie Horlogère (SSIH). Lemania became the exclusive movement supplier for Omega, and by 1936, half a million Lemania movements were in production at any given time.

During this period, two of the first truly modern movements created especially for wristwatch chronographs emerged. The first was the Lemania CH 13-based Omega 28.9 CHRO launched in 1932 that measured 29mm in diameter and was characterized by its beautiful V-shaped bridge. The second was the Lemania CH 15-based 33.3 CHRO that measured 33.3mm in diameter and used a distinct U-shaped bridge that would also appear in the Omega 321. This was launched in 1933. Omega watches with the 33.3 CHRO are much sought after as the calibre represents an important precursor to the 2310 or 321. Note that it is clear both the 28.9 and 33.3 movements were in development before the SSIH consolidation.

The linage of Omega’s chronograph calibers that gave rise to the 2310, aka CH 27, which was soon christened the 321; note that the orientation of the 27 CHRO is a mirror reflection of the preceding 18 CHRO, 39 CHRO, 28.9 CHRO and the 33.3 CHRO (Image: omegaforums.net)

What has been the source of some discussion is that the orientation of both these movements is opposite that of the 18‴ and 39 CHRO. Meaning that if you had a 33.3 or 28.9 CHRO-powered watch and looked at it from the front and removed the dial, the balance wheel would appear at six o’clock. In the 18‴ and 39 CHRO watches, it would appear at 12 o’clock. Most people feel that this is because the 33.3 and 28.9 were wristwatch movements while 18‴ and 39 were pocket-watch movements, bt quite honestly, no one really knows.

Interestingly, when Albert Gustave Piguet set to work on the Lemania 2310 or CH 27, he flipped the orientation back so the balance was once again at 12 o’clock. What was the impetus for the creation of this new movement?

First, a new movement was needed for wristwatches which had completely taken over from pocket watches in popularity and had considerably smaller diameters. So Piguet was tasked with creating the smallest movement he could and arrived at the 27mm diameter. Second, Lemania and Omega were focused on the creation of a new workhorse chronograph that would be small and slim, and most importantly, feature a 12-hour totalizer that was essential for the burgeoning activities in both auto racing and aviation. Finally, the 2310 would be one of the first critical projects under the newly consolidated SSIH group. So, on all levels, the Lemania 2310 was really a movement that symbolized the advent of the modern world in the 20th century.

The Two-Counter Version Vs The Three-Counter Version

In 1942, the calibre 2310 or CH 27 was introduced in two versions: the CH 27-17P two-counter version (with seconds and chrono minutes) and CH 27-12P three-counter version (with seconds, chrono minutes and 12-hour totalizer). Adding to the complexity, the movement came in a 17-jewel version, which formed the base of the Omega 321, and also a 21-jewel version with swan-neck regulator known as the Lemania 2320. To put this in perspective, all haute de gamme brands that adopted the movement in the 1980s and 1990s would use the 21-jewel, swan-neck-regulator version 2320 but with two counters, so to be exact, they used the CH 27-17P. Omega used the 17-jewel, three-counter version 2310, or to be precise, the CH 27-12P for their Calibre 321.

The calibre 2310 is truly a thing of beauty. Let’s look at some of its central characteristics.

1. The massive balance wheel beats at 18,000vph, although many brands have increased this vibrational speed to 21,600vph.

2. The column wheel is the command centre of the chronograph. All the best chronographs use column wheels to activate the sequence of start, stop and reset.

3. The intermediate bridge holds down the wheel for the minute counter and the all-important chronograph central seconds wheel. Note that this bridge has been the subject of a great deal of artistic expression for different brands. The Patek Philippe bridge is distinctly V-shaped. The Vacheron Constantin bridge is somewhere between a V and Y shape. The Roger Dubuis bridge is fully Y- or wishbone-shaped. The Omega 321 bridge is U-shaped. The Breguet is somewhere between a U and a Y.

4. The reset hammers for the chronograph wheel and minute counter are one piece.

5. The chronograph coupling lever, seconds wheel (co-axial with the seconds wheel that is driving the continuous seconds indicator) and the intermediate or drive wheel are all placed in a compact arrangement just beside the chronograph second wheel.

6. The Lemania 2310 has a very high level of adjustability, including the depth of engagement for the drive wheel.

Long before the 1969 birth of the automatic chronograph movement, prototype Lemania 2310 self-winding movements may very well have been the world’s very first automatic chronographs (Image: Northernman from omegaforums.net)

One image that has intrigued many movement aficionados is the image of prototype automatic Lemania 2310-based movements. These are dated to 1947, but were never put into production. But it is interesting to see that a full 12 years before the launch of the Zenith El Primero, there were already early experiments into an automatic-winding integrated chronograph.

Omega Speedmaster calibre 321 (1957–1968)

There is no brand more synonymous with the amazing Lemania 2310 (CH 27-12P) than Omega. In 1946, Omega created its own version of this movement and dubbed it the calibre 321. The Speedmaster chronograph was initially created to meet the demands of a burgeoning auto-racing culture that was sweeping the United States and Europe. While the movement had been used in several Omega models before, it found its true home in a new chronograph with the first-ever tachymetric scale engraved on the bezel — the Speedmaster. Legend, of course, goes that this watch was subsequently certified as the official timepiece for NASA. Every watch that received this certification and that went into space was one of the following three models: the 105.003, the 105.012 and the 145.012. And they all used the calibre 321.

Speedmaster references 105.003, 105.012 & 145.012 were three references certified for manned space missions by NASA; every one of these watches featured a calibre 321

The third generation of the Speedmaster, the 1963 ST 105.003 (Image: Christies.com)

The Speedmaster ref. ST 105.012 with a pulsation scale bezel (Image: Christies.com)

The Speedmaster ref. ST 145.012 with a DON bezel (Image: Christies.com)

As homage to this movement’s incredible history, Omega’s brilliant CEO Raynald Aeschlimann brought the movement back last year. It is constructed in a purpose-built section of the Omega manufacture. Every movement is assembled, regulated, finished and cased by one individual watchmaker, who then personally signs the warranty card for that 321 watch. Aeschlimann is quick to point out that the modern calibre 321 is not a gussied-up Lemania 2310 ébauche but a ground-up development.

Omega’s 2019 New Original Calibre 321 with PVD treated bridges and plates in the hue of Omega’s Sedna™ Gold (©Revolution)

Speedmaster Moonwatch 321 Platinum

The Speedmaster Moonwatch 321 Stainless Steel (©Revolution)

The Speedmaster Moonwatch 321 Stainless Steel is powered by the Omega New Original Calibre 321 with PVD treated bridges and plates in the hue of Omega’s Sedna™ Gold (©Revolution)

Says Aeschlimann, “When we asked Speedmaster collectors what their dream was, the vast majority said they wanted to see a resurrection of the calibre 321. So we thought if we are going to do this, we have to do it the right way.” Rather than using an existing Lemania 2310 ébauche from their Swatch Group sister brand Breguet, Omega decided to completely and accurately reverse-engineer the original 321 calibre, down to its exact specifications. In order to do this, Omega’s team, helmed by Aeschlimann, had to petition the Swatch Group’s board of directors.

From a purely financial perspective, it made no sense to resurrect the 321, especially not in the way Omega intended, which involved a slice-by-slice 3D tomographic scan of the movement found in astronaut Gene Cernan’s actual ST 105.003 timepiece that he wore to the Moon and that is now found in their museum. The cost of this scan alone was over one million Swiss francs. To replicate the exact pallet with its very specific guard pin, Omega also had to approach Nivarox to recreate this component down to its finest details.

“The only way we could truly respect this incredible movement and all its devotees, as well as the legions of fans passionate about the Speedmaster’s history, is [to] go down to these painstaking details and bring the 321 back in its full integrity and authenticity. That is the only way for us here at Omega,” says Aeschlimann.

For Omega CEO Raynald Aeschlimann, the re-creation of the calibre 321 had to be exact. This involved a slice-by-slice 3D tomographic scan of the movement found in astronaut Gene Cernan’s actual ST 105.003 that he wore to the Moon and that is now in the Omega museum. The cost of this scan alone was over one million Swiss francs (©Revolution)

Patek Philippe calibre CH 27-70 (1985–2011)

In the ’80s, the Lemania 2310 became a canvas of expression for watchmaking’s most revered maisons. The first of these was Patek Philippe. Amazingly, Philippe Stern used the Lemania 2320 (CH27-17P) in 1985 to replace the Valjoux 13-130 of the 2499, creating the amazing 3970 perpetual calendar chronograph. In Patek-speak, the movement is called the CH 27-70. Thanks to the Lemania 2320’s 27mm diameter, he was actually able to make a smaller watch at 36mm in comparison to the 2499’s 37.5mm diameter.

The 3970 marked the return of the the Lemania 2310/2320 to Patek Philippe’s highest expression of watchmaking with the CH 27-70 (Image: sothebys.com)

Launched in 1985 by Patek Philippe, the 3970 perpetual calendar chronograph marked the return of the Lemania 2310/2320, now elevated to the highest rung of watchmaking, seen here is a first series 3970, exclusively made in yellow gold with baton hour markers, most easily identified by its snap caseback that meant that this watch was not water-resistant to any degree (Image: sothebys.com)

The snap caseback of the first series Patek Philippe ref. 3970 (Image: sothebys.com)

The chronograph-only version — the 5070 launched in 1998 — would conversely be the largest Patek chronograph ever serially produced at 42mm. These two watches show the amazing adaptability of this movement for watch designs. The CH 27-70 continued to be used in the successor to the 3970, the larger 40mm-diameter 5970 designed by Thierry Stern, and also in the iconic perpetual calendar with split-seconds function, often considered one of the Holy Grails of watch collecting, known as the Patek Philippe 5004, produced from 1996 to 2011.

The Patek Philippe ref. 5070, at 42mm the largest wrist watch chronograph to feature the CH 27-70 (Image: Phillips.com)

Display caseback of the 5070 showcasing the CH 27-70 within (Image: Phillips.com)

Eric Clapton’s Custom, Breguet-Numeral Patek Philippe Ref. 5970G (©Revolution)

Wei’s Patek Philippe Perpetual Calendar Chronograph ref. 5970 in rose gold with a unique chocolate dial (©Revolution)

Caseback view of Wei’s Patek Philippe Perpetual Calendar Chronograph ref. 5970 showcasing the Lemania-based CH 27-70 (©Revolution)

A pink gold Patek Philippe split second ref. 5004 formally the property of musician, Eric Clapton sold by Phillips back in 2016 at their Hong Kong Watch Auction: THREE (Image: Phillips.com)

Breguet calibre 533.3 (circa 2000s–present day)

The ’70s was a turbulent period in Switzerland with the watch industry reeling from the effects of the Quartz Crisis. At the very bleakest moment, one extraordinary man emerged to save the Swiss watch industry. His name was Nicolas G Hayek.

Hayek had established a reputation as a restructuring expert when he was asked to oversee the liquidation of two groups, Allgemeine Schweizerische Uhrenindustrie AG (ASUAG) and the previously mentioned SSIH. But instead of liquidating them, he realized he could save them if he could make them more efficient. The first thing he did was consolidate them both into one group named the Société de Microélectronique et d’Horlogerie (SMH, later to be renamed the Swatch Group).

The late, industry titan, Nicolas G Hayek

When he did his analysis of ASUAG, Hayek was shocked to discover the profound inefficiencies of the 100-plus companies, all of which were doing separate R&D, marketing and assembly. He introduced the concepts of streamlining and verticalization, and in a lesson clearly learned by the German auto industry, invested in the standardization of parts. In this process, he discovered a project on making simple, efficient mechanical watches using 51 parts instead of the usual hundreds of parts, and he named this the Swatch watch, and using dynamic marketing techniques, created the first mass shift against the Quartz Crisis.

Lemania came out of the SSIH group in 1981. It was renamed Nouvelle Lemania and was purchased by Breguet in 1992. Swatch Group purchased Breguet in 1999 and with it, Lemania. The brilliance of Nick Hayek was to always verticalize production. Just as Blancpain has Frédéric Piguet, Breguet had Lemania. To be fair, Lemania would have had much of its production dedicated to its historical ally, Omega, which was also Hayek’s motivation for purchasing Breguet. Amongst the various movements in the Lemania arsenal that were lying dormant like a sleeping giant was, of course, the amazing Lemania 2310/2320. As such, the creation of beautiful Classique-cased chronographs using the venerable Lemania 2320 seemed only natural. The modern version of this watch is the reference 5287.

The Lemania 2320-equipped Breguet 5287 is one of my favorite dress chronographs for horological purists, it has all of the iconic design language created by Breguet (©Revolution)

The Breguet 5287 is a watch for horological purists. It has all of the iconic design language created by Abraham-Louis Breguet. Says Emmanuel Breguet, the head of patrimony and marketing for the manufacture, “At the time, watches were very baroque in decoration. He [A-L Breguet] was the first to introduce a new, clean, modern design language. He applied subtly different decorations to each sector of the dial to aid in clarity.”

The 5287 uses snailing for the chrono minute counter and an amazing circular barleycorn decoration for the continuous seconds counter (note that this features a two-sided hand read off a 30-minute track). The dial receives Paris hobnail guilloché, while the hour indexes are on a circular brushed track with the tachymeter on an opaline flange. The entire dial is solid gold and a masterwork of guilloché main or hand guilloché, where these patterns are engraved using hand-guided, ancient rose-engine machines. The round case has the same fluted caseband that A-L Breguet used to decorate his pocket watches.

Now, flip the watch over and revel in the glory of the Lemania 2320. Interestingly, this is the only version of the Lemania 2320 that uses 24 jewels. Breguet also uses the swan-neck regulator but increases the vibrational speed to 3Hz.

The Breguet 5287 is powered by the calibre 533,3 (Breguet’s version of the Lemania 2320) (©Revolution)

Breguet’s version of the Lemania 2320 is the only one with 24 jewels, possibly owing to the power reserve indicator on the dial side (©Revolution)

Vacheron Constantin Calibre 1140/1141 (1989–Present Day)

Since 1989, Vacheron Contantin has been able to create some of the most handsome chronographs using the 21-jewel Lemania 2320 as its base. This movement was dubbed the Vacheron calibre 1140. According to Vacheron Constantin, the 1140 was based on the 17-jewel 2310 model. But the confusion arises from the fact that when I’ve looked at calibre 1140-equipped Vacheron watches, they appeared to have 21 jewels and swan-neck regulators, leading to me believe that this work was undertaken in-house. The calibre 1141, however, uses the Lemania 2320 as its base, which comes with 21 jewels and a swan-neck regulator. Note that none of these movements had a Geneva Seal.

Over the last three decades, the manufacture has used the 1140/1141 for three models — the Historiques Chronograph, the Malte Chronograph and the Patrimony Traditionnelle, where it has also been combined with a perpetual calendar.

Of these watches, one of the most sublime is the 47100, a magnificent skeletonized version of the Patrimony Chronograph. These watches can be purchased in the secondary market for around USD 20,000 to USD 30,000, which is a considerable bargain considering their original price is four times that.

Vacheron Constantin introduced in 2006 a strictly limited edition of 75 timepieces of the “Malte Chronograph” cased in platinum, part of the of the “Collection Excellence Platine”, the watches are fitted with a platinum dial (Image: Christies.com)

Caseback of the Vacheron Constantin Malte Chronograph “Collection Excellence Platine” showcasing the calibre 1141 (Image: Christies.com)

The Vacheron Constantin Traditionnelle Chronograph Perpetual Calendar was introduced at SIHH 2017 in platinum and pink gold

The Vacheron Constantin Traditionnelle Chronograph Perpetual Calendar was powered by the calibre 1142 QP, the Manufacture’s take on the Lemania-based chronograph with an incorporated perpetual calendar

Vacheron Constantin Historiques Cornes de vache 1955 ref. 5000H/000P-B058 in platinum that was launched at Watches & Wonders 2015, in Hong Kong; the watch was powered by the calibre 1142 (©Revolution)

Vacheron Constantin Historiques Cornes de vache 1955 ref. 5000H/000R-B059 in 18K 4N pink gold was launched in 2016

Vacheron Constantin Historiques Cornes de vache 1955 ref. 5000H/000A was a limited edition of 36 pieces made for Hodinkee in 2017, in stainless steel

Vacheron Constantin Historiques Cornes de vache 1955 ref. 5000H/000A-B582 in stainless steel was launched in 2019, the watch comes fitted on a dark brown calf leather with Serapian patina

Vacheron Constantin Historiques Cornes de vache 1955 is powered by the hand-wound calibre 1142, an interpretation of the Lemania 2310 for the 21st century (©Revolution)

Pièce Unique Vacheron Constantin Historiques Cornes de vache 1955 created for Wei, back in 2017 with a yellow gold case and dial (©Revolution)

Wei’s pièce unique Vacheron Constantin Historiques Cornes de vache 1955 is as well powered by the Calibre 1142 (©Revolution)

Wei’s pièce unique Vacheron Constantin Historiques Cornes de vache 1955 was delivered with four dial options (©Revolution)

Although the halcyon manufacture launched its own in-house chronograph movement in the calibre 3300 in 2015, it still continues to use this charming historic movement in what can be considered one of Vacheron Constantin’s most successful chronographs of all time, the magnificent Cornes de Vache which takes its name from its stylized lugs. The Cornes de Vache is inspired by the 1955 reference 6087. Amusingly, the original 35mm watch from 1955 featured a Valjoux 23 movement which measured 29.5mm as opposed to the 27mm diameter calibre 1142 of the modern watch.

The Cornes de Vache is to me one of the most desirable and iconic modern men’s dress chronographs on the market. Launched in 2015, the watch was a brilliant modernization of the smaller 6087. Says Emilie Vuilleumier, the designer who was tasked with the watch’s creation, “The original watch has very rounded lugs. But we wanted to add a more dramatic sharper profile to the edge to add a sense of dynamic tension to the overall design.” Flip the watch over and revel in the most beautiful chronograph movement ever created.

Note that the movement in the Cornes de Vache is caliber 1142. How does the 1142 differ from the 1141? Well, it is the in-house-produced version of the movement. Richemont acquired the rights to manufacture this movement when it purchased Roger Dubuis in 2008. From a technical perspective, the most obvious difference between the 1142 and its predecessor is the use of a free sprung balance wheel which is clearly inspired by the Patek Philippe CH 27-70.

Roger Dubuis calibres 56 and 65 (1995–2003)

Roger Dubuis secured the rights to manufacture the Lemania calibre 2310/2320. He used this movement extensively, with his brand being the only one to feature a monopusher version of this movement.

In 1995, Roger Dubuis, a watchmaker who’d spent many seminal years at Patek Philippe and gained renown for creating the world’s first double-retrograde perpetual calendar along with Agenhor founder Jean-Marc Wiederrecht, launched his eponymous brand. His Hommage model can only be described as his expression for vintage Patek Philippe design.

He created his Lemania 2320-based chronograph in three sizes — 34mm, 37mm and 40mm — demonstrating the remarkable design adaptability of the movement. His Lemania movements received the Geneva Seal and were certified as chronometers by the observatory at Besançon. They are designated RD56 for the regular two-pusher version and RD65 for the monopusher version. I believe that Roger Dubuis was the only modern watchmaker and brand to make a monopusher version of the Lemania 2320.

Dubuis used the movement in other models, including his baroque Sympathie case which was combined with the double-retrograde perpetual calendar, and notably, the Easy Diver Chronograph, making it the only dive watch to receive the Geneva Seal. OK, here’s the important thing about the 2320 movement found in the Roger Dubuis watches. Dubuis managed to secure the rights to produce the movement in-house. In 2008, when Richemont Group bought Roger Dubuis, it obtained the rights to produce this movement.

Wei’s personal Roger Dubuis Hommage Chronograph H40 matte black dial and polished white gold applied Breguet numerals (©Revolution)

Caseback view of Wei’s personal Roger Dubuis Hommage Chronograph H40 showcasing the Lemania-based manual-winding Cal. RD 56 (©Revolution)

Of the various Lemania 2320-based Roger Dubuis chronographs, my favorites are the H40 (40mm size) Roger Dubuis Hommage Chronographs. I’ve spoken at length about how, from a design perspective, I find these to be some of the most beautiful watches of the modern era, in particular related to the combination of Breguet numerals, pointed baton markers, applied dots and perfectly designed typography, as seen here on my personal watch.

Image Comparison of My Patek 5970, Vacheron Cornes de Vache, Roger Dubuis H40 & a Breguet 5287 On Loan

The micro-sandblasted treatment on this Vacheron Constantin’s chronograph train is unique to this watch and does not appear on serially produced timepiece (©Revolution)

Frequency

Vacheron Constantin Calibre 1142: 21,600vph or 3Hz

Patek Philippe Calibre CH 27-70: 18,000vph or 2.5Hz

Breguet Calibre 533,3: 21,600vph or 3Hz

Roger Dubuis Calibre RD56: 18,000vph or 2.5Hz

Swan Neck vs. Free Sprung

All movements, save the Patek CH 27-70, used the swan-neck regulator of the Lemania 2320. Note that when Vacheron Constantin transitioned from the 1141 to the in-house calibre 1142, they also shifted from a swan-neck regulator to a free sprung balance wheel.

The Vacheron Constantin Calibre 1142 has a frequency of 21,600vph (3Hz), sports a free sprung balance wheel and its intermediate bridge is a mix of a V and Y (©Revolution)

The Patek Philippe Calibre CH 27-70 Q has a frequency of 18,000vph (2.5Hz), sports a free sprung balance wheel and its intermediate bridge is a distinct V (©Revolution)

The Breguet Calibre 533,3 has a frequency of 21,600vph (3Hz), sports a swan neck regulator and its intermediate bridge is a mix of a U and Y (©Revolution)

The Roger Dubuis Calibre RD56 has a frequency of 18,000vph (2.5Hz), sports a swan neck regulator and its intermediate bridge is a distinct Y or wishbone shape (©Revolution)

The 2020 Omega Calibre 321 has a frequency of 18,000vph (2.5Hz) and has an intermediate bride that is U-shaped (©Revolution)

Geneva Seal

The Vacheron Constantin 1142, Patek CH 27-70 and Roger Dubuis RD56/65 all receive the Geneva Seal. One of my favourite elements of the Vacheron movement is the Maltese cross-shaped cap for the column wheel. Even though this is in high relief, I am going to assume that it still qualifies as a “cap” as seen in the other Geneva Seal watches. Note that the Vacheron calibers 1140 and 1141 were not Geneva Seal movements.

Style of Intermediate Bridge

This is a funny name because it actually is the bridge that holds the seconds wheel and the minute counter wheel. You can immediately distinguish this because of the small heart cams that are used to reset these two wheels as well as the reset levers poised just beside them. This is the bridge that holds down the wheel for the minute counter and the all-important chronograph central seconds wheel. Note that this bridge has been the subject of a great deal of artistic expression for different brands. The Patek bridge is distinctly V-shaped. The Vacheron bridge is somewhere between a V and Y shape. The Roger Dubuis bridge is fully Y- or wishbone-shaped. The Omega 321 bridge is U-shaped. The Breguet is somewhere between a U and a Y.

Lastly, it is worth pointing out that the Patek Philippe CH 27-70 underwent a greater degree of modification. The clutch lever that carries the intermediate wheel is pivoted concentrically to the drive wheel for better transmission efficiency, forming a distinctive S shape, with its free end interacting with the column wheel. At the same time, it has a curved return spring that runs alongside the clutch lever, resulting in a more intricate and refined look. Hence, although they are all based on the legendary Lemania movement, they differ in their levels of refinement, corresponding to their respective price points.