The Leroy Osmior Chronometre a Tourbillon L100: a French masterpiece
Giovanni Di Biase18 March 2021
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Defining the Leroy Osmior Chronometre a Tourbillon as the 2015 finest example of high quality watchmaking is not an exaggeration and I also reckon that no other existing watch can currently combine together the perfect concept of classical manufacturing and advanced high tech features like this timepiece does. Since its foundation in 1713 the French watch manufacturer (now based in Switzerland) Leroy has been awarded a whopping number of gold medals (385 to be precise) at the famous Chronometry Competitions. To fully appreciate this new addition to the Osmior collection one needs to either spend a bit of time with the maestro, who crafted this masterpiece, or, like I did, to have a good chat with Olivier Mueller, CEO of the brand.
The most interesting aspect of this piece lies in the fact that if you are not at all familiar with both the history of watch manufacturing and the old decorations of historical pieces (some of which, coming from the Leroy museum, were on display at the brand's booth in Basel) it will take you time to grasp the extreme high quality of this timepiece. Some of its features will surely remind you of the fine culture of the high end French watch manufacturing and of some of the maison's creations for the French royals. The same aura of magnificence of the Leroy Osmior Chronometre a Tourbillon can be found in some timepieces by Moser & Cie also, but I still think that because of the deep historical meaning of the brand this unique masterpiece is of even higher quality and its only competitor is probably Breguet.
Let's take a look at the dial: its grill motif resembles that of a desk clock exclusively created for Queen Marie Antoniette.
Under the grill, painted on a gold disc with a “Grand Feu” decoration, lies a small lozenge representing the power reserve indication, but how do you actually read these details? The disc sporting the lozenge moves on itself and rotates 300° between 11 and 1 o'clock to track the 72 hours of power reserve (when the watch is fully wound). This is the first secret of the watch's originality and it gives you an idea of the maison's concept hidden behind the creation of this item. By manually winding the crown you'll discover a second surprise which will make you fully understand the refinement of this timepiece: turn the watch to face its back case side, open the lid and enjoy a full view of the L100 caliber. This discovery brings me back to my initial thoughts: this item is actually a winner. The first action proves that this is a timepiece featuring a dead seconds complication, while thesecond one, accompanied by Mr Mueller's comments, is self-explanatory.
The L100 caliber feature would actually deserve a separate in-depth review but I will try to summarize in few lines its main characteristics, some of which actually require a good knowledge of watch manufacturing techniques and history. This item is a tourbillon and is made by 953 different parts, its pillar based crafting technique draws inspiration from the 18th century's marine chronometers. The barrell bridge is finely decorated with a brushing technique which uses silver powder, a traditional method no longer used in watchmaking.
The caliber is mounted on a direct impulse escapement (a big direct impulse coupled with a small indirect one) that draws inspiration from the “Duplex” escapement created and patented by Pierre Le Roy: an ingenious mechanism allowing the self-compensation of thermal variations. All the watch's technical features have been designed with the history of watchmaking (decorations included) in mind and with a clear intent of reaffirming the maison's leadership in chronometry making and its second to none savoir-faire. The balance wheel sports four regulating screws and a spiral, with a double inner and outer terminal curve ensuring a perfect isochronism by allowing a perfect concentric oscillation along its vertical axis. The spiral is actually produced in-house by a company owned by the Festina Goup, to which LeRoy belongs too, that is fully capable to produce every single component of the watch.
The 2,5Hzfrequency is ensured through a balance wheel of large dimensions which has been specifically designed to provide a long term rate precision. The Leroy Osmior Chronometre a Tourbillon is the third watch in a row that I have reviewed this year to use a constant force mechanism. This device is fully integrated within the escapement and is equipped with a fusee-chain mechanism used to equalize the energy release from the barrell during the fully 72 hours of power reserve. I could go on talking about this for hours.
In making the Leroy Osmior Chronometre a Tourbillon it seems like Leroy has pulled out of its hat the best of the expertise and patents achieved in almost three centuries of watchmaking history and has created a sort of book of refined technique fully surpassing the skills and quality of all its competitors. This timepiece is very unique and when you hold it in your hands it is as if you were looking at a masterpiece created for a king. The manufacturer adopted the finest details (like for instance the champlevè decoration with painted Roman numerals on the dial), mixed them with a classic taste coupled with mechanical complications, and finally updated everything with original and innovative solutions to create a special wristwatch for a few elected people.
The strength of this maison is that it is able to convey the idea of classic far better than any other watchmaker. For Leroy it is all about content: sober and fine decorations aimed at a client looking for watchmaking at its best, an avid connoisseur who is not interested in showing off his refined nature to the mass, but only to another equally competent enthusiast. This is a timepiece which has been merely conceived for the sake of its owner and for this very reason I sense that the Palladium 950 version would be more appealing than the blue and red gold one. When it comes to the brand's image this timepiece represents a clear step forward if compared to the actual Leroy's collections ,which are definitely excellent but are actually unable to convey such a successful message as does the Leroy Osmior Chronometre a Tourbillon.
(Photo credit: courtesy of Leroy; Horbiter®'s proprietary photo-shooting)
A mechanical watch feature displays, on the dial or the case back, the remaining power in a watch movement, showing the length of time until the timepiece must be rewound.
Crown
Placed on the case side, it winds the mainspring. When pulled out, it also sets the time and the date. A screw-down crown increases water resistance and protects the movement…
Complication
The addition of any mechanical complication to a movement that usually displays the time.
Case
It encases the mechanical movement and is crafted in one or more parts. It can also be a single piece, as with some professional diving watches, or made of unconventional…
Balance wheel
A part of a mechanical watch that oscillates, dividing time into equal portions.
Frequency
It is the number of oscillations of the regulating organ. It is divided into hours, mechanical watches, and quartz watches.
The most interesting aspect of this piece lies in the fact that if you are not at all familiar with both the history of watch manufacturing and the old decorations of historical pieces (some of which, coming from the Leroy museum, were on display at the brand's booth in Basel) it will take you time to grasp the extreme high quality of this timepiece. Some of its features will surely remind you of the fine culture of the high end French watch manufacturing and of some of the maison's creations for the French royals. The same aura of magnificence of the Leroy Osmior Chronometre a Tourbillon can be found in some timepieces by Moser & Cie also, but I still think that because of the deep historical meaning of the brand this unique masterpiece is of even higher quality and its only competitor is probably Breguet.
Let's take a look at the dial: its grill motif resembles that of a desk clock exclusively created for Queen Marie Antoniette. 
Under the grill, painted on a gold disc with a “Grand Feu” decoration, lies a small lozenge representing the 
The L100 caliber feature would actually deserve a separate in-depth review but I will try to summarize in few lines its main characteristics, some of which actually require a good knowledge of watch manufacturing techniques and history. This item is a tourbillon and is made by 953 different parts, its pillar based crafting technique draws inspiration from the 18th century's marine chronometers. The barrell bridge is finely decorated with a brushing technique which uses silver powder, a traditional method no longer used in watchmaking.
The caliber is mounted on a direct impulse escapement (a big direct impulse coupled with a small indirect one) that draws inspiration from the “Duplex” escapement created and patented by Pierre Le Roy: an ingenious mechanism allowing the self-compensation of thermal variations. All the watch's technical features have been designed with the history of watchmaking (decorations included) in mind and with a clear intent of reaffirming the maison's leadership in chronometry making and its second to none savoir-faire. The 
The 2,5Hz 
In making the Leroy Osmior Chronometre a Tourbillon it seems like Leroy has pulled out of its hat the best of the expertise and patents achieved in almost three centuries of watchmaking history and has created a sort of book of refined technique fully surpassing the skills and quality of all its competitors. This timepiece is very unique and when you hold it in your hands it is as if you were looking at a masterpiece created for a king. The manufacturer adopted the finest details (like for instance the champlevè decoration with painted Roman numerals on the dial), mixed them with a classic taste coupled with mechanical complications, and finally updated everything with original and innovative solutions to create a special wristwatch for a few elected people.
The strength of this maison is that it is able to convey the idea of classic far better than any other watchmaker. For Leroy it is all about content: sober and fine decorations aimed at a client looking for watchmaking at its best, an avid connoisseur who is not interested in showing off his refined nature to the mass, but only to another equally competent enthusiast. This is a timepiece which has been merely conceived for the sake of its owner and for this very reason I sense that the Palladium 950 version would be more appealing than the blue and red gold one. When it comes to the brand's image this timepiece represents a clear step forward if compared to the actual Leroy's collections ,which are definitely excellent but are actually unable to convey such a successful message as does the Leroy Osmior Chronometre a Tourbillon.
