Ultra‑thin doesn’t have to mean fragile. The steel Octo Finissimo pairs a 6.4 mm case and 100m water resistance with a platinum microrotor movement and one of the best‑resolved integrated bracelets at any price. Legibility is fine in daylight, there’s no lume, sizing can be fussy, and the movement doesn’t hack. If you value architecture, comfort, and credible everyday specs in a design that isn’t a clone, this is it.
The brief
The satin‑polished steel Octo Finissimo with blue sunburst lacquer dial, integrated steel bracelet, and BVL 138 microrotor movement. 40 mm width, 6.40 mm thickness, screw‑down crown with ceramic insert, 100 m water resistance.
The "S" steel iteration adds real-world durability while keeping the collection's calling card - thinness as a feature in its own right.
Case and finishing
Bulgari’s layered octagon still looks like architecture on the wrist. Mixed satin‑polished surfaces catch light without shouting. The step‑bezel and crisp case facets read cleanly at arm’s length and precisely under a loupe. Practical upgrades - screw‑down crown and 100m WR - make it a genuine daily. Thickness is 6.40 mm, so it slides under any cuff yet doesn’t feel wafer‑fragile.
Link articulation is tight and even. If you do the “over‑the‑finger” test, the bracelet drapes uniformly rather than collapsing in sections - the kind of detail watch geeks obsess over. The feel backs up the visual complexity.
Dial and legibility
Blue lacquer with a sunburst finish that runs radially from center. Applied rhodium markers and Arabic numerals at 12 and 6 keep the dial from going flat; skeletonized hands fit the theme. No date, no minute hashes. Result: clean look, quick reads, but setting to the exact minute takes patience. Also no lume - note this if you want night visibility.
Movement - BVL 138 Finissimo
The architecture is a 2.23 mm‑thin automatic with platinum microrotor and small seconds at ~7:30. 3 Hz, 60‑hour power reserve. Finishing is restrained but coherent - wide striping, neat anglage on the balance bridge, and that dense micro‑rotor adding visual weight. The caliber does not hack. You can “back‑set” to align the seconds if you care, but there’s no true stop‑seconds. The microrotor is the point of pride here - efficient, beautiful, and fundamental to the watch’s proportions.
Bracelet and clasp
Integrated steel bracelet with a butterfly‑style deployant that sits flush and adds almost no visual thickness. There’s no push‑button release and no micro‑adjust; fine sizing relies on small links rather than on‑the‑fly adjustment. Comfort is excellent once sized, though hot‑cold wrist changes may send you a half‑link hunting.
On the wrist
The watch disappears under a shirt and feels like a cuff - broad, flat, stable. The blue dial shifts from inky to electric depending on light, giving the otherwise minimal layout some life. As discussed on A Matter of Time, thinness genuinely functions like a complication here - you feel the engineering every time the bracelet articulates. “Just go to a store and try an Octo Finissimo - you’ll get the feeling.”
Comparisons
Could be compared to the Royal Oak 15510 or the Nautilus 5711 lineage. The Octo plays a different game stylistically yet competes on finishing of the case and bracelet and everyday wearability. Time+Tide positioned this exact ref as the best modern challenger during its launch year - a fair framing if you want integrated steel without a years‑long wait list mindset.
You buy the Octo Finissimo in steel because you want the experience of thinness without babying the watch. The bracelet tolerances and microrotor deliver daily joy, the architecture is unmistakable, and the practical upgrades make it a confident one‑watch‑collection candidate - as long as you’re okay with no lume, no hacking, and a bit of bracelet‑sizing fuss.
Specs - at a glance
- Case - 40 mm width, 6.40 mm thick, satin‑polished steel, screw‑down crown with ceramic insert, sapphire front and back, 100 m WR
- Dial - Blue lacquer, sunburst, applied indices and 12/6 numerals, small seconds ~7:30
- Movement - BVL 138 microrotor automatic, 3 Hz, 60‑hour power reserve, 2.23 mm thick
- Bracelet - Integrated steel, butterfly clasp, no micro‑adjust
- Notable changes vs early Finissimo - water resistance up from 30 m to 100 m with a small thickness tradeoff, improved daily utility.
References
- Bulgari official spec page for Ref. 103431 - case 6.40 mm, 100 m WR, BVL 138 with platinum microrotor, blue sun‑brushed lacquer dial with rhodium applied indexes. (Bulgari)
- Fratello - launch coverage and spec sheet for Ref. 103431 - 40 mm, 6.4 mm, 100 m WR, price context at launch. (Fratello Watches)
- Time+Tide - hands‑on impressions of the blue dial steel ref - dial tone, bracelet feel, and competitive framing versus RO/Nautilus. (Time+Tide Watches)
- Monochrome - movement dimensions and technical notes - BVL 138 at 2.23 mm, 3 Hz, 60 h. (Monochrome Watches)
- Fratello “Why I Bought the Octo Finissimo S” - notes on non‑hacking, minute‑track precision when setting. (Fratello Watches)
- A Matter of Time, Episode 4 (YouTube) discussing bracelet tolerances, thinness as a “complication,” and try‑on experience.
