The development of the ultra-thin tourbillons is the holy grail of high-end watchmaking, an exalted task that only a few watchmakers would even attempt. Abraham-Louis Breguet invented the tourbillon more than 220 years ago, so it is not surprising that the company he founded is at the forefront of this ongoing race. Six years ago Breguet launched the Classique Tourbillon Extra-Plat Automatique 5377, a rose gold watch that was just 7 mm thick based on a revolutionary new movement, Caliber 581, which was only 3 mm thick. A year later came the platinum version, and in 2017 the Classique Tourbillon ExtraPlat Automatique 5367, all based on the original extra-thin movement.

Breguet engineers have now taken the innovation one step forward with the Breguet Classique Tourbillon ExtraPlat Squelette 5395. It is powered by the newly created extra-thin Caliber 581SQ, a skeleton version of the original self-winding tourbillon movement. A masterpiece of watchmaking, its development involved the removal of as much as 50 per cent of the material from the existing movement. The skeleton design within an 18K gold caliber pushes the limits of watch design to its extremes. The challenge was to hollow out the materials as much as possible, while preserving the build of the movement and the technical properties of the various components.

This required not just complex technical readjustments, but also craftsmanship of the highest order in areas like engraving, engine-turning, and anglage. For instance, the rotor was placed on the periphery of the plate, saving on thickness while at the same time preserving a clear view of the mechanism. The tourbillion itself has been completely reworked. The titanium carriage now engages directly with the wheel train, not via the intermediary of a pinion at its base, and the silicon escapement has been given a distinct angled shape which has achieved considerable saving on space.

The ultra-lightweight carriage weighs no more than 0.290 grams in total, but is equipped with an outstanding power reserve of 80 hours. At 7.7 mm, the watch itself is slightly thicker than its immediate predecessor thanks to the ‘domed glass-box’ version of the crystal on top. Water-resistant to 30 metres, Classique Tourbillon Extra-Plat Squelette 5395 is available with a grey movement in a rose gold case, or with a rose movement in a platinum case.