Bulgari made its debut at Watches & Wonders this year, having previously exhibited outside the fair. It was a fitting occasion to launch the Octo Finissimo Ultra Tourbillon, the thinnest tourbillon watch ever at just 1.85 mm thick. Housed in the brand’s signature matte grey titanium case and limited to just 20 pieces, the Ultra Tourbillon is paired with an equally thin and silky titanium bracelet.

Bulgari is deeply invested in its leadership in ultra-thin watchmaking, and the Ultra Tourbillon shows the brand is willing to do whatever it takes to own as many records in this field as possible.

Initial thoughts

Despite its record-breaking slimness, there was surprisingly little buzz about the Ultra at Watches & Wonders. This may be due to record fatigue, since the previous record was set just last year by the Piaget AUC Tourbillon. It could also be due to the diminishing returns of these types of records, which are now being broken by almost imperceptible margins.

On its exterior, the Ultra Tourbillon is quite similar the 1.7 mm-thick Octo Finissimo Ultra introduced last year. It features a 40 mm case made from a combination of titanium and tungsten carbide, and is impressively open-worked, revealing just about every wheel and pinion on the dial side of the watch. But this watch is all about the headline figure of its 1.85 mm thickness, which endows the Ultra Tourbillon with a delicate, almost weightless feel.

The case in profile. Image – Bulgari

Like all ultra-thin record-holders, the new BVF 900 flying tourbillon movement features a baseplate that is integral to the case back. This is a bit like some MotoGP engines that use the engine block as a structural part of the frame. Racing teams do this to save weight, and watchmakers do it to save precious tenths of millimeters.

Surprisingly, the movement beats at 4 Hz, which is a lively rate for any tourbillon, let alone something this thin. The energy consumption of the tourbillon can be roughly estimated by the 16% difference in power reserve between the BVL 180 and BVF 900, which runs for up to 42 hours rather than 50.

World records always come at a cost, and in this case that cost is US$678,000. This is about what I expected and less than half what Richard Mille charges for the RM UP-01, but it’s difficult to rationalise this pricing when records are falling this quickly. Regardless, Bulgari expects there are at least 20 people who will feel the need to own the thinnest tourbillon ever, and they’re probably right.

How they did it

The quest for ultra-slimness always starts by eliminating unnecessary layers in the watch, starting with the case back. The BVF 900 features a monobloc tungsten carbide main plate that also serves as the case back.

The rest of the movement’s components are spread out in a single layer across the dial, further minimising thickness. This gives the watch a highly technical look that enables the wearer to trace the flow of power visually from the mainspring barrel to the hands and, separately, to the flying tourbillon that is powered from its edge.

Another space-saving trick involves the crown, or should I say crowns, because there are two. To keep things simple, the operations for winding and setting have been divided between two crowns integrated into the case back, one on each side. The crown at eight o’clock winds the mainspring barrel, while its counterpart at three o’clock is used to adjust the time.

Because there’s nowhere for most of the components to hide, the user can clearly see how their inputs are working inside the watch, an effect that is both engaging and educational.

Though Bulgari hasn’t announced it officially, the Octo Finissimo Ultra Tourbillon and BVF 900 movement were developed with the help of Concepto, the Swiss movement specialist that was also behind the earlier ultra-thin Octo watches. This explains the familial lineage that is apparent in the movement construction.

But there are costs to ultimate slimness. For example, the addition of the tourbillon meant losing some chronometric precision. This may seem counterintuitive, but the extra inertia of the tourbillon cage absorbs energy that would otherwise be transmitted to the balance. Furthermore, tourbillon movements (necessarily) have smaller oscillators than their peers with fixed escapements. As a result, the BVF 900 is not a COSC-certified chronometer like the BVL 180.

Another trade-off is in the way the balance is shock protected. In an ordinary mechanical watch, the balance staff rotates between jewels that are mounted with small springs, enabling them to absorb shocks, preventing damage to the movement.

But this traditional construction gets in the way of extreme thinness, and brands have found different ways to deal with this. For example, Piaget solved this problem by using a flying balance with a single pivot that rotates in a robust ball bearing.

Bulgari has found its own solution, borrowed from the BVL 180, that involves the use of flexible arms for the upper tourbillon cage. While this is likely more than enough to protect the movement in a watch like the Ultra Tourbillon that will probably not be subjected to everyday wear, this solution doesn’t feel as mature as the ball bearing pivots utilised by Piaget.

Impressively, the BVF 900 features some relatively traditional characteristics that are seldom seen on ultra-thin watches, like prominent skeletonisation, stacked hour and minute hands, and a grande sonnerie-style winding click.

Unfortunately, these traditional touches result in a few components that appear dangerously thin. For example, the hour and minute hands showed some distortion at some angles, likely resulting from when they were press-fit onto the cannon pinion.

Last year, the Piaget AUC Tourbillon impressed me because it felt more robust than it looked, offering a coin-like heft and sense of durability. In contrast, the Tourbillon Ultra feels somewhat fragile, on account of its skeletonisation and light weight.

The AUC  featured a solid case back with a small window for the tourbillon, while the Tourbillon Ultra offers three individual panes of sapphire crystal, revealing the back of the dial, the flying train wheels turning in ball bearings, and the entirety of the tourbillon cage. It’s truly an impressive display, but it increases the sensation of delicacy.

In terms of finishing, the look is very neat but clearly industrial. And it couldn’t really be any other way with a watch this thin; most of the components are simply too delicate to accommodate much in the way of anglage. But overall the monochromatic look works very well and suits the brutalist look of the Octo Finissimo case and bracelet.

Closing thoughts

The Tourbillon Ultra is an undeniably impressive watch. Not only are its dimensions record-breaking, but it offers an engaging, technical design that looks the part, and it feels almost weightless on the wrist. The bracelet is another nice touch that helps it stand out from the rest of the ultra-thin field, which are universally fitted with straps.

That said, the Tourbillon Ultra feels more like a concept watch than a real, wearable product, and some of the compromises made to achieve its 1.85 mm thickness feel like just that.

Key facts and price

Bulgari Octo Finissimo Tourbillon Ultra
Ref. 103834

Diameter: 40 mm
Height: 1.85 mm
Material: Titanium and tungsten carbide
Crystal: Sapphire
Water resistance: 10 m

Movement: BVF 900
Functions: Hours, minutes, and seconds
Frequency: 28,800 beats per hour (4 Hz)
Winding: Manual wind
Power reserve: 42 hours

Strap: Titanium bracelet with folding clasp

Limited edition: 20 pieces
Availability: From Bulgari boutiques
Price: $678,000 excluding taxes

For more, visit bulgari.com.