Calibre 101 has been one of the breakthroughs not just in the history of Jaeger-LeCoultre, but also in the whole of horology. The smallest mechanical calibre ever – created in 1929 and famously worn by Queen Elizabeth II for her coronation in 1953 – has got its latest version dazzling in pink gold and pink sapphires and diamonds. Limited to just three pieces, the new 101 Secrets (Ref. Q2872310) continues the maison’s heritage of secret watches, where the time is discreetly concealed within an elaborate jewellery design.

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The watch has been crafted in 18K pink gold and features a double rivière-style bracelet set with 124 brilliant-cut pink sapphires weighing approximately 16.39 carats. The stones are graduated in both size and colour across 10 sizes and seven shades, ranging from intense cyclamen to pale blush. A contrasting band of grain-set white diamonds separates the two rows of sapphires, while the stones are claw-set to maximise light and enhance their colour and brilliance. The case sides are also set with sapphires and diamonds, with the diamonds continuing along the bracelet. In total, the watch has 904 brilliant-cut diamonds weighing approximately 13.26 carats. The gem-setting work was completed at Jaeger-LeCoultre’s Métiers Rares™ atelier and required 163 hours. When revealed, the time is displayed on a luminous white mother-of-pearl dial surrounded by a rectangular pink-gold bezel set with diamonds.

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The secret mechanism is concealed within the rows of gemstones and is operated by a hidden button at 6 o’clock. When the button is pressed and held, part of the bracelet opens like a book to reveal the dial. Releasing the button causes the dial to disappear again beneath the ribbon of pink sapphires. A second miniature mechanism is hidden within the clasp.

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The movement, Calibre 101, was built on the Duoplan architecture, where instead of arranging the gears horizontally, a two-layer stacking was used. By placing the escapement on one plane and the barrel and gear train on another, the design reduced the space required by the mechanism, while its mainspring was wound through a flat crown integrated into the caseback.

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The original Calibre 101 measured just 14 mm long, 4.8 mm wide, and 3.4 mm thick. It contained 74 components and weighed barely one gram. Its balance oscillated at 21,600 vibrations per hour, or 3 Hz, while the mainspring provided a 33-hour power reserve. The movement remains the world’s smallest rectangular manually wound mechanical movement.

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Also Read: A Challenge. A Legacy

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Over the past nine decades, advances in materials, gear-train design, and production methods have improved the calibre, but its fundamental dimensions and architecture remain unchanged. The current fifth-generation Calibre 101 contains 98 components, each of which must be individually produced and adjusted because of its extremely small dimensions. A specialised atelier is dedicated to the movement, with only a small number of watchmakers possessing the skills required to assemble it. It takes approximately 40 hours to assemble the 98 components, limiting annual production to only a few dozen movements.

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The new 101 Secrets measures 29.07 mm x 12.22 mm x 9.88 mm, while the 18K pink-gold bracelet is designed for a 160 mm wrist.

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Price upon request.

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Images: Jaeger-LeCoultre

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