The New World’s Thinnest Tourbillon Watch, the 1.85mm Bulgari Octo Finissimo Ultra Tourbillon

We are undoubtedly in a golden age of the ultra-thin watch, with records continuously being shattered and timepieces at a level of thinness that would have been almost unimaginable just a few years ago… At Watches and Wonders 2024, Piaget clinched the record for the thinnest tourbillon ever with its Altiplano Ultimate Concept Tourbillon, measuring a mere 2mm. Well, just a year later, Bulgari recaptures this title – and the bragging rights. Meet the Bulgari Octo Finissimo Ultra Tourbillon, a 1.85mm watch that’s now the new world’s thinnest tourbillon watch available. 

The Bulgari Octo Finissimo series is one of the most striking watch collections of the last decade. This impressive saga turned Bulgari into one of the unrivalled masters of ultra-thin watchmaking, topping one record of thinness after another.

• 2014 – Octo Finissimo Tourbillon – thinnest Tourbillon movement 1.95mm – case 5.00mm – calibre BVL 268
• 2016 – Octo Finissimo Minute Repeater – thinnest Minute Repeater, movement 3.12mm – case 6.85mm – calibre BVL 362
• 2017 – Octo Finissimo Automatic – thinnest Automatic movement 2.23mm – case 5.15mm – calibre BVL 138
• 2018 – Octo Finissimo Tourbillon Automatic – thinnest Automatic and thinnest tourbillon, movement 1.95mm – case 3.95mm – calibre BVL 288
• 2019 – Octo Finissimo Chronograph – thinnest Chronograph, movement 3.30mm – case 6.90mm – calibre BVL 318
• 2020 – Octo Finissimo Tourbillon Chronograph – thinnest Chronograph Tourbillon, movement 3.50mm – case 7.40mm – calibre BVL 388
• 2021 – Octo Finissimo Perpetual Calendar – thinnest Perpetual Calendar, movement 2.75mm – case 5.80mm – calibre BVL 388
• 2022 – Octo Finissimo Ultra – thinnest mechanical watch 1.80mm – calibre BVL 180
• 2024 – Octo Finissimo Ultra COSC – thinnest mechanical watch 1.70mm – calibre BVL 180
• 2025 – Octo Finissimo Ultra Tourbillon – thinnest tourbillon watch 1.85mm – calibre BVF 900

At 1.85mm, the Bulgari Octo Finissimo Ultra Tourbillon is now the world’s thinnest tourbillon watch – the previous record was held by the 2mm Piaget Altiplano Ultimate Concept Tourbillon. Before that, the thinnest Tourbillon was the Octo Finissimo Tourbillon Automatic at 3.95mm. 

The new Octo Finissimo Ultra Tourbillon is housed in a 40mm x 1.85mm titanium case with an ultra-hard tungsten carbide mainplate/caseback (the usually separated two elements are here fused in one single part), which is partially skeletonised (more on this later). Instead of a standard crown, two horizontal steel knobs are placed on each side of the case – one for winding and the other for time setting. 

This paper-thin watch is powered by the new hand-wound calibre BVF 900. The design and technical concept are clearly derived from the Octo Finissimo Ultra and Ultra COSC. Developed together with movement specialist Concepto, this achievement pushed the limits of ultra-thin manufacturing, trimming down the components and working with the most extreme tolerances. It involved innovative engineering, reimagining each component, its architecture and its functions. One guiding principle has been to avoid having different layers in the watch architecture and to rearrange all functions on the same horizontal plane. 

Just like the Piaget Altiplano Ultimate Concept, the caseback is used as the movement’s base plate. The use of ball bearings wherever possible explains the low jewel count (15). For example, rollers drive the rotation of the tourbillon cage or the large barrel delivering 42 hours of power reserve. This is slightly lower than for the no-tourbillon Ultra COSC, as the mechanism requires more energy but is still comfortable enough.

However, the desire to create a different, skeletonized design and the use of a tourbillon regulator required significant adjustments to the BVL 180 movement, in particular, to create space for the tourbillon regulator. The hours and minutes displays have been brought together at 2 o’clock, replacing the regulator-like display with separate time indications of the “no-tourbillon” Ultra. 

Then comes another technical challenge – how to build a tourbillon regulator thin enough to fit within a 1.85mm watch? Instead of a conventional construction where it is held by its underside, plus eventually with an upper bridge, the tourbillon cage is guided peripherally by miniature ball bearings (9). The tourbillon cage itself is a mere 1.18mm, which involved working with super-tight tolerances and re-imagining different parts. The wheel driving the cage serves as its bottom bridge and several of the principles used for the classic Octo Finissimo Ultra have been implemented. The oscillator incorporates a flat spring, it has no index but features gold adjustment weights. It does not feature a conventional anti-shock device but incorporates a flexible bridge (integrating the stud holder) that will deform in the event of a shock.

The Bulgari Octo Finissimo Ultra Tourbillon is worn on a titanium bracelet fitted with a concealed folding clasp. It is released in a limited edition of 20 pieces. The price is set at EUR 750,000. The battle for thinness is not over.

For more information, please visit www.bulgari.com.