Bianchet redefines modern Haute Horlogerie with the B 1.618 UltraFino, a timepiece where precision engineering meets mathematical poetry. Crafted around the Golden Ratio (1.618), this ultra-thin timepiece houses Bianchet’s first automatic flying tourbillon movement, the UT01 caliber, entirely made from titanium. At just 8.9mm thick, its curved tonneau-shaped case follows a 1.2mm lug-to-lug curvature, delivering an effortlessly ergonomic fit that balances elegance with resilience. Strength and refinement converge as the UltraFino defies convention, with an impressive 5,000Gs shock resistance and 5 ATM water resistance, ensuring durability without compromise. Available in two expressions, one showcases a skeletonized movement with exquisite hand-finishing, while the other features the Golden Diamond dial, a modernized Clou de Paris motif. Both variants incorporate Bianchet’s signature rubber seam between the bezel and case middle. At the heart of the watch, the UT01 movement is an ultra-thin feat of engineering at 3.85mm thick and 8 grams light, featuring one of the rarest horological constructions—an automatic flying tourbillon in titanium with a Fibonacci-inspired gold rotor. Every component adheres to 1.618 proportions, reinforcing Bianchet’s commitment to aesthetic perfection. Additionally, the fully integrated titanium bracelet, a rare feat for a tonneau-shaped case, enhances the watch’s seamless fluidity, while a vulcanized rubber strap with a titanium deployant buckle provides an alternative refined look. The B 1.618 UltraFino stands as a testament to the Golden Ratio’s enduring influence, fusing ultra-thin tourbillon mastery, contemporary sportswear ergonomics, and architectural beauty. Whether skeletonized or featuring the Golden Diamond dial, it remains a bold statement of proportion, performance, and timeless elegance.