A lot has changed since Sylvain Berneron unveiled the first renders of the Mirage last October. He has since departed from Breitling to dedicate himself fully to his own brand and has already delivered the first batch of watches. Additionally, the Mirage is a shoo-in for the time-only category at the GPHG.

The watch is simply exceptional in the metal, a rarity in watchmaking where mechanics and aesthetics seamlessly meld into one another and onto the wrist. Falling in love with it happens so reflexively that it’s easy to miss just how sophisticated the design actually is and how the movement was conceived to extract the best possible performance with a shaped design.

Yet even before the dust has settled, Berneron is onto his second watch with a brand new ultra-thin calibre 215 and stone dials. While the original Mirage measures 38mm in length, 34mm in width and 7mm high, the new Mirage 34mm is significantly smaller at 34mm by 30mm by 7mm. It comes in two stunning variations – white gold with a lapis lazuli dial, and yellow gold with tiger’s eye. 24 pieces in each variation will be made a year. By the time you read this, the first batch for 2025 has already been allocated.

One thing worth emphasising about Berneron is that he has adopted a very measured approach to production. The designs that have been presented are not limited editions; instead, they are here for the long run and will evolve organically with incremental updates and improvements over time.

A Masterclass in Shaped Design

The Mirage 34mm retains the same asymmetrical shape derived from Fibonacci numbers. While many watches claim inspiration from mathematical phenomena like the golden ratio or the Lamé curve, such applications are often more superficial. Very rarely do they demonstrate a deep mathematical integration. In contrast, the Mirage is conceptually sophisticated and adheres to the Fibonacci sequence in an abstract way, resulting in a genuinely intriguing form that warrants admiration. It’s truly uncommon for a watch’s design alone to inspire such intrigue and it’s fair to say that it’s usually history and mechanics that drive study.

The Fibonacci sequence is a related but distinct mathematical concept from the golden ratio. The golden ratio, denoted by the Greek letter φ (phi), is an irrational number approximately equal to 1.6180339887. In contrast, the Fibonacci sequence is a series of numbers where each number is the sum of the two preceding ones, starting with 0 and 1. However, as the sequence progresses, the ratio of successive Fibonacci numbers ((e.g., 21/13, 34/21) approaches the golden ratio.

Understanding how Fibonacci numbers guide the design of the Mirage might seem peripheral, but the considerable ingenuity involved is worth getting a clear view of.

To summarise briefly, the design of the Mirage begins with a base circle (Fig. 1), representing the conventional watch case. This circle serves as the foundation for subsequent design manoeuvres, ensuring that the resulting watch remains both familiar and wearable.

From the center of this circle, a Fibonacci spiral is incorporated. A Fibonacci spiral is a visual representation of the Fibonacci sequence, where each arc represents a quarter-circle. It is constructed by placing quarter-circle arcs in squares whose side lengths are Fibonacci numbers. Each successive square is adjacent to the previous one, either along its side or next to the last square added. Once the squares are laid out, arcs are drawn inside each square. The arc in each square forms a quarter-circle and connects two opposite corners. These arcs collectively form the spiral. The size of each new square is based on the sum of the side lengths of the two preceding squares, following the Fibonacci sequence. As the squares get larger, the arcs become larger, creating the characteristic spiral that expands outward.

Utilising points c1, c2, and c3 of the spiral, a scalene triangle is derived and these points form the centre of three circles with diameters that adhere to the Fibonacci sequence 5, 8, 13. Tangents are applied at the intersection points of the large circle with the base circle and at the points where c2 and c3 cross. These tangents are used to derive points c4 and c6 (Fig. 2), using a radius equivalent to the distance from c2 to c3. Additionally, using the diameter of the large circle, two more circles are added to encompass both the base circle and the small circle, rounding off the case, with their central axes forming points c5 and c7. Then, a second Fibonacci spiral is introduced (Fig. 3), passing through points c4, c5, c6, and c7. From this, the start of spiral, the central axis for the subsidiary seconds hand is established.

While the resulting shape may appear organic, arbitrarily shaped for visual effect, it is very much based on determinable fixed rules.

Stone Dials

Apart from the size, the key difference between the original Mirage and the 34mm version is that it no longer has a sector dial and is devoid of numerals. This allows the quality of execution and materials to speak for themselves. Achieving the thinness required for a watch dial while maintaining the integrity of the stone is a daunting task. Furthermore, the dial is made of a single piece of Tiger’s Eye and Lapis Lazuli stone, meaning the recessed sub-dial are carved by hand directly in the stone, leaving behind a residual thickness of 0.35mm in the sub-dial while the rest is 0.7mm.

Lapis lazuli is primarily composed of lazurite, with inclusions of calcite, pyrite, and other minerals. While its deep blue colour is striking, the presence of these inclusions can create weak points within the stone. It is relatively brittle compared to other gemstones. The risk of chipping or cracking during cutting and polishing is significant, especially when trying to achieve the thinness required.

Tiger’s eye, on the other hand, is composed of silicon dioxide (chalcedony) with a unique fibrous structure that creates its characteristic chatoyancy (a shimmering, cat’s eye effect). Although tiger’s eye is tougher than lapis lazuli, it can still be brittle when cut too thin. The fibrous nature means that if the stone is not handled correctly, it can split or fracture along its layers. Skilled lapidaries must exercise caution during cutting to avoid damaging the stone. Berneron explains that the failure rate in production for both Tiger’s Eye and Lapis Lazuli dials is 60 percent.

Calibre 215

The Calibre 215 is named for its height; it measures just 2.15mm high, which is 0.18mm slimmer than the first calibre. It is worth clarifying that the initial Calibre 233 was conservatively stated to have a power reserve of 60 hours. However, further testing has confirmed a power reserve of 72 hours, with a beat rate of 21,600 vph. The main feat in the new Calibre 215 is that it has managed to retain a power reserve of 72 hours, thanks to an asymmetrical base plate which can accommodate a larger barrel.

The image below illustrates a crucial aspect of movement design, highlighting the relationship between movement footprint, barrel diameter, and power reserve. It demonstrates how an asymmetrical shape with a relatively small increase in the movement’s footprint (from 356 mm² to 410 mm², a 15% increase) leads to a dramatic improvement in power reserve.

A modest increase in the barrel’s diameter enables it to store significantly more energy. This is due to the geometric properties of a cylinder, where an increase in diameter has an exponential effect on volume (and therefore the energy storage capacity) compared to the linear change in surface area or footprint. The volume of the barrel is calculated using the formula for the volume of a cylinder: V = πr²h. Thus, with a 15% increase in footprint, the diameter of the barrel could be increased by 30%, and the volume (which correlates to the stored energy and torque) increases by approximately 70%. This 70% increase in volume leads to a 90% increase in power reserve, from 38 hours to 72 hours.

However, the Calibre 215 has a significantly smaller balance wheel with an inertia of just 1.45mg/cm2, which is likely the lowest in watchmaking. Hence, the frequency was increased to 25,200 vph.

To bring the seconds hand where it should be, there are four wheels in the gear train with the last wheel driving both the escape wheel pinion and the seconds wheel. Given the extremely limited space on this tiny movement, the hour and minute hands are not inverted in this new model and the balance is no longer free-sprung as it is too sensitive for regulation with weights, which is why a regulator stud is used.

The base plate and bridges are once again in solid 18k gold. The base plate and escape wheel bridge have a frosted finish while the white gold barrel and centre wheel bridges are decorated with a guilloché pattern that mimics Geneva stripes. The balance bridge, on the other hand, is made from steel for greater stability. In short, a shaped movement this thin and tiny with an outsize power reserve is outstanding and nothing quite like it exists anywhere else in watchmaking.

In all, I can think of few watches that manage to be this daring yet sophisticated. It trades in elegance and refinement but at the same time it has an impressive movement, made to eke out the longest power reserve in the case of the Mirage 34mm. Its Fibonacci-derived form makes it one of the most thought-provoking designs to come down the pike, and it redefines what collectors should expect from modern horology.

Most of all, it is hard not to be impressed by the mind behind the Mirage, who has virtually thought about everything. If you look at the case back, for instance, there’s a step, meaning the watch was designed to accommodate a bracelet!

The Mirage 34 is priced at CHF 51,000 for 2026.

Tech Specs

Movement: 18k gold manual winding Calibre 215; 72 hours of power reserve; 3.5 Hz or 25,200 vph
Functions: Hours, minutes and small seconds
Case: 18k yellow gold or white gold; 30mm x 34mm x 7mm, water-resistant to 30m
Dial: Lapis Lazuli or Tiger’s eye
Strap: Barenia leather strap with 18k gold buckle
Price: Preferential price for 2025 model year CHF 48’000 excluding VAT (sold out), CHF 51’000 excluding VAT for 2026 model year.