To achieve such a feat, with a minute-repeater no less, a tremendous amount of research and design was required as this type of complication is one of the most difficult to produce. And to fit a minute-repeater movement inside a 6.85 mm thick case was, of course, an incredible challenge for the watchmakers in Le Sentier.
The special Bulgari introduced the world’s thinnest tourbillon wristwatch in 2014. Two years later, they have debuted another record-setting timepiece called the Octo Finissimo Minute Repeater, which is currently the thinnest minute repeater in the world.
At 3.12 mm in thickness, the movement is thinner than two-quarters stacked on top of each other. Which again, we have to call out, considering this is a chiming watch.
To achieve the desired level of sound quality, in such a small area, the use of titanium was required for the case and even the dial. Titanium has a low-density, which ensures excellent sound diffusion, and so it was a natural choice for the case (which measures a svelte 40 mm x 6.85 mm). Moreover, to further improve the acoustic resonance, a titanium dial, with incised cut-outs for each hour marker and for the small seconds display, allow the sound to protrude from the movement below and into the rest of the case, amplifying the sound. The result is sound that is much louder, clearer, and more consistent than you would expect from such an ultra-thin case.
Inside, manually wound caliber 362 beats at 3Hz (21,600 vph), with a power reserve of 42-hours. The movement is decorated with Geneva stripes, perlage, and chamfering – fully visible through the clear caseback.
Additional details include a titanium crown set with a ceramic insert, titanium slide, and water-resistance of 30 meters. Apart from the facetted hands with diamond polished tips, all surfaces are entirely matte finished. Production is limited to 50 pieces. Each piece comes with a vulcanized black alligator leather strap with triple-blade titanium folding clasp.
Interestingly, the Bulgari Octo Finissimo Minute Repeater beats the Vacheron Constantin Patrimony Contemporaine Ultra-Thin Calibre 1731 – which was previously the world’s thinnest minute repeater – by a considerable margin (3.12 mm vs. 3.9 mm for the movement, and 6.85 mm vs. 8.09 mm cased up).