Jean Lassale was a Swiss watch company that designed the Calibre 1200, featuring the thinnest mechanical watch movement: 1.2 mm. In the 1970s, Pierre Mathys, a master watchmaker in La Chaux-de-Fonds, designed and built the prototype of a revolutionary watch calibre, with the aim of making the world’s thinnest watch. To achieve this feat, Mathys based his design on the work of Robert Annen, who had previously come up with the idea of using ball bearings in small-scale watchmaking. Mathys decided to do away with the bridges and counter-pivot, and instead use ball bearings for the axle.

Today, the thinnest watch on the market remains the Jean Lassale 1200 (1.2 mm thick) and, in its automatic version, those equipped with the calibre 2000 (2 mm thick). These two models were both manufactured in the Bouchet-Lassale SA workshops in Geneva from 1976 to 1979, before disappearing when the company was taken over by Seiko.

The calibre 1200, with its automatic version the Calibre 2000, were first presented at the Foire Internationale de l’Horlogerie in Basel in April 1976. This mechanical, handwound movement has a diameter of 20.4 mm, and a thickness of 1.2 mm. There is an automatic version which is 2.08 mm thick). It holds 14 ball-bearings. Each one uses 0.20 mm balls. These ball-bearings are inserted in a platine which is 1.2 mm thin. The calibre 1200 (and its automatic version 2000) were built from 1976 to 1979 in the factory that the company Bouchet-Lassale SA had built on 30, rue des Voisins in Geneva, Switzerland. The gold cases came from the « Ateliers réunis », a company also located in Geneva.

The patent for this watch movement was applied in Switzerland on 1976, February 18. It was then applied in the USA on January 2, 1979 under the code US4132061A. The Abstract of the patent is :
An extra-thin manually or automatically wound watch movement in which at least one wheel is pivoted in an overhang position by means of a single-race miniaturized ball bearing.

• Brand: Jean Lassale Genève
• Reference: 1200
• Production year: late 70’s
• Movement: caliber 1200, manual winding, chronometer certified, bridges decorated with geneva waves, thinnest mechanical movement ever made
• Case: 18K solid yellow gold, 32mm (without crown)
• Dial: champagne with vertical satin brushed finish, gold stick hands and gold index hour markers
• Bracelet: original Jean Lassale glossy black croco strap with original Jean Lassale 18K yellow gold pin-buckle
• Condition: excellent, almost like new, about 9/10
• Accessories: original precious wood box and private certificate of authenticity from our company, NO other papers
• Shipping: we can ship Express and fully insured from Switzerland, upon request from EU to EU. Otherwise a pick-up in Lausanne, Geneva or Zürich area is also possible. For any import taxes issues, feel free to contact us before purchasing
• A real collector’s piece and an exploit of miniaturization, still unbeatable today, 45 years later, a real investment value and unique piece