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The Osmior Bal Du Temps marks a bold new chapter for L. Leroy, fusing 240 years of heritage with uncompromising haute horlogerie. A poetic blend of sound, precision, and artistry, it reaffirms the maison’s place among watchmaking’s true innovators.

For the very first time, the storied French watchmaker L. Leroy is stepping onto the stage of Geneva Watch Days, marking both a long-awaited revival of the brand and its monumental 240th anniversary this year. For those that may not know, L. Leroy is a haute horlogerie brand that quickly became famous for supplying timepieces to the likes of Marcel Proust, Queen Victoria, Carlos Santos-Dumont, Napoleon Bonaparte, and Marie Antoinette.

L. Leroy was established in Paris in 1785 by Charles Leroy and was renowned for being a supplier of marine chronometers and highly complicated pocket watches. Throughout the 19th century, L. Leroy was at the forefront of precision chronometry, producing marine chronometers that were some of the finest creations in the world. Becoming synonymous with exacting precision, the maison was viewed as one of the leaders of French haute horlogerie. One of the most famous pieces for the brand was the Leroy 01, which was created in 1900. At the time, it was considered the most complex pocket watch in the world, being host to 24 complications (astronomical functions, perpetual calendars with a four-digit year display, a minute repeater, chronograph, etc). It held that record until Patek Philippe’s Calibre 89 was unveiled in 1989.

While L. Leroy isn’t as widely known in modern watchmaking as Swiss giants like Breguet, Patek, or Vacheron, it is widely respected for its French horological heritage and contributions to precision navigation and scientific timekeeping. With the brand now celebrating its 240th anniversary this year, and its re-emergence onto the world stage at Geneva Watch Days, L. Leroy is poised to remind collectors and enthusiasts of its historic importance.

The timepiece starting off this new era is the Osmior Bal Du Temps. Placed into the brand’s Osmior collection, the timepiece features complications of the highest technical level, such as the Tourbillon and Minute Repeater. The Osmior Bal Du Temps will be produced in limited quantities and be manufactured exclusively for L. Leroy in Geneva.

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“These new creations are the beginning of a new era for L.Leroy, whose desire is to keep its glorious past
alive while fully respecting the brand’s DNA. Great attention is therefore paid to the aesthetic canons
that define it, the exquisite finishes that enhance its fascinating beauty and the intricate mechanics with
their impressive complications.”
L. Leroy

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Case Design

L. Leroy is offering the case of the Osmior Bal Du Temps in three various materials: the noble 18K 5N red gold, prestigious platinum, and the lightweight and contemporary grade 5 titanium. Measuring 43mm in diameter and with a thickness of 13.6mm, the proportions of the Osmior Bal Du Temps remain compact even with the highly technical movement sitting inside.

The “tambour” shaped case, which is a signature design of the Osmior collection, has a recessed middle section between the bezel and caseback, while the lugs are chamfered and slightly flared to taper elegantly at the ends. The crown features grooved notches for better grip, while having an interlaced double “L” brand logo. L. Leroy has given the case further refinement, with the rear sapphire crystal’s securing ring combining flat and domed segments with six fixing screws. These embossed sections, framed by polished profiles and sandblasted surfaces, are finished with engraved reliefs that reinforce the watch’s identity.

Dial Design

The dial is described as “a delight for the eyes” by L. Leroy, and it’s quite easy to see why. The dial is a stunning display of high craftsmanship, paying homage to L. Leroy’s historical heritage and the tradition of Swiss high-end watchmaking, with every detail being accurately designed to meet the highest standards of this art. The open-work dial showcases in a poetic manner the intricate mechanics of this complex movement, which features the minute repeater and the flying tourbillon. Only highly-skilled watchmakers are able to execute these two complications to perfection, resulting in perfectly harmonious sounds and excellent chronometric precision.

What is noteworthy about the Osmior Bal Du Temps is that there is only a single hand that indicates the hours. The minutes are indicated by the beautiful acoustics of the minute repeater, which is activated by a slide located at 9 o’clock. This type of time reading is inspired by the historic “a tact”, a watch made for Prince Emil Maximilian Leopold August of Hesse around 1810.

The hour ring has been given a sunray brushed finish, with the colour of the ring changing depending on the case material. The 18k 5N red gold case gets an anthracite hour track with L. Leroy Arabic numerals in gold decal, the platinum case gets a blue hour track with L. Leroy Arabic numerals in white decal, and lastly, the titanium case gets a rhodium-plated silver hour track with the L. Leroy Arabic numerals in black decal. All three variants highlight L. Leroy’s ability to offer the same horological canvas in three very different expressions of character.

Movement

The highly complex movement that powers the Osmior Bal Du Temps is the hand-wound movement: the Calibre L610SQ. Produced exclusively in Geneva, the proprietary movement operates at a frequency of 3Hz (21,600 VpH) and is equipped with a unique barrel that guarantees a power reserve of no less than 90 hours! The flying tourbillon cage, which is composed of 76 parts, is embellished with the logo-shaped, polished titanium upper bridge.

While much of the caseback is closed off, the craftsmanship on display is still exquisite. The movement plate is adorned with L. Leroy’s signature, while also featuring the inscriptions “Calibre L601SQ” and “Manufacture a Geneve,” showcasing that it’s produced entirely in Geneva. The hammers of the minute repeater mechanism are also beautifully displayed, boasting exquisite finishing, with mirror polishing on the surface and anglage on the bevelled edges.

Initial Thoughts

L. Leroy’s return to the world stage could not have been more fitting. With a 240-year history, the brand is reminding collectors and watch enthusiasts exactly why it stood among the leaders of haute horlogerie, not only for its ties to royalty, but also for its scientific pioneering efforts and record-setting pocket watches. With the unveiling of the Osmior Bal Du Temps at Geneva Watch Days 2025, the brand is bringing back its horological identity with only the single hand display combined with minute repeater indications, a daringly poetic execution.

I personally love skeletonised watches, and the Osmior Bal Du Temps has executed this concept perfectly, keeping the dial readability crisp and clear while showcasing the high-craftsmanship of the movement from the L. Leroy watchmakers. The poetic harmony of the minute repeater, the technical virtuosity of the flying tourbillon, the impressive 90-hour power reserve, all wrapped in the elegant tambour case design, give the Osmior Bal Du Temps a timeless and bold look. It’s an opening statement in a new era for L. Leroy’s that feels true to the brand’s DNA: unconventional, historically aware, and unapologetically haute horlogerie.

Specification: L. Leroy Osmior Bal Du Temps – 18k 5N Red Gold (Ref. LL305/1)

International Recommended Retail Price: Price On Request.

Availability: Limited production. Available through L. Leroy boutiques. Head to montres-leroy.com for more information

Specification: L. Leroy Osmior Bal Du Temps – Platinum (Ref. LL306/1)

International Recommended Retail Price: Price On Request.

Availability: Limited production. Available through L. Leroy boutiques. Head to montres-leroy.com for more information

Specification: L. Leroy Osmior Bal Du Temps – Grade 5 Titanium (Ref. LL307/1)

International Recommended Retail Price: Price On Request.

Availability: Limited production. Available through L. Leroy boutiques. Head to montres-leroy.com for more information