To celebrate its 20th anniversary, Greubel Forsey presents its 10th Fundamental Invention, the Nano Foudroyante EWT —Experimental Watch Technology. The mechanism’s energy is managed at the nanojoule scale, significantly reducing the number of components and the overall dimensions. The result is a 37.9 mm timepiece that combines the world’s first perpetual Nano Foudroyante with Greubel Forsey’s first flying tourbillon and manual wind flyback. This timepiece, set in a white gold and tantalum case, will be limited to just 11 pieces.

The first Fundamental Invention by Robert Greubel and Stephen Forsey was launched in 2004, marking the Atelier’s commitment to research and invention. For over 20 years, this focus has been at the heart of all Greubel Forsey’s Fundamental Inventions and timepieces. Today, Greubel Forsey’s research is even more fundamental, aiming to completely rethink the approach to the conception of a timepiece. This endeavor demonstrates a major technological leap, comparable to the transition from tower clocks to wristwatches.

Originally, horological instruments were large and public. Over time, they became transportable —table clocks, marine chronometers—, then portable with pocket watches, and finally wearable with wristwatches. This evolution reaches its peak today with nanomechanics, a revolution Greubel Forsey is pioneering. This new Fundamental Invention is the most technologically disruptive, not only for Greubel Forsey but also for the universe of mechanical watchmaking.

What is nanomechanics? It is a realm beyond the miniaturization of components to the nanometric scale. When we talk about nanomechanics, we’re talking about controlling energy on a nanojoule scale within a mechanical movement. This revolution in energy management within a caliber allows for a drastic reduction in both energy consumption and the number of components.

To demonstrate the feasibility of nanomechanics, Greubel Forsey has reinvented the foudroyante second. Its hand completes one revolution per second, dividing it into segments according to the movement’s frequency. In this Nano Foudroyante, each oscillation of the 3 Hz balance wheel produces two beats, totaling six beats per second, allowing the hand to divide the second into six distinct segments. This is an energy-intensive complication by nature. However, by managing energy on a nanojoule scale, Greubel Forsey has radically rethought its design and construction. Compared to a traditional foudroyante that consumes 30 μJ (microjoules) per jump, the Nano Foudroyante operates with only 16 nJ (nanojoules) per jump, reducing energy consumption by a factor of 1,800. The mechanism’s volume is therefore reduced by 90%. Here, the focus is not just on measuring fractions of a second but as a proof of concept for a completely new approach to watchmaking, which is why this Nano Foudroyante was chosen to be a perpetual display.

This is just the foundation and not the end result: this 10th Invention is powered by a manual-winding flyback movement. This complication presented by Greubel Forsey, includes a column-wheel control within the strong architectural design and exceptional finishing, a signature of Greubel Forsey.

It eliminates the entire gear train required in a traditional foudroyant to divide the second, as the information is sourced directly, distributing and managing the energy from the movement through a minimal number of low-inertia wheels. Fewer components mean less volume, this Nano Foudroyante EWT is very compact, with 428 components, and the movement measures no more than 31 mm in diameter within a 37.9 mm case —the smallest ever built by Greubel Forsey.

Greubel Forsey also preserves its essential aesthetic signatures, including polished relief engravings of “Nano Foudroyante” and “Greubel Forsey” on a hand-hammered background, hand-satin-finished white gold, and a highly architectural movement. This masterpiece displays the movement around its column wheel with rare 3D monobloc geometry, visible through the back. The timepiece is engraved with “2004 – 2024” and “20th Anniversary” to mark this milestone.

The 37.9 mm 5N white gold case offers an additional surprise, with a bezel and back crafted from tantalum—a first for Greubel Forsey, who have never used this material before. Known for its gray-blue sheen and complexity in machining and finishing —with a melting point above 3000 degrees Celsius—, tantalum requires rare expertise.

True to Greubel Forsey’s passion for the tourbillon, this Nano Foudroyante is integrated within a flying tourbillon —the first ever made by Greubel Forsey. Finally, although this flying tourbillon rotates constantly, the Nano Foudroyante’s dial remains permanently aligned towards twelve o’clock for optimal readability. Together with the flyback, these three features complete Greubel Forsey's 10th Fundamental Invention: a Nano Foudroyante, set within a flying tourbillon, with an oriented reading axis.

The timepiece will be made in a limited edition of just 11 pieces in this inaugural, refined version, emphasizing its disruptive technical character and highlighting the personality of a timepiece brilliantly conceived in the EWT (Experimental Watch Technology) laboratory. This masterpiece displays the movement around its column wheel with rare 3D monobloc geometry, visible through the back.

Sticker Price CHF 465,000 Swiss Francs — approx USD 535,000. For more info on Greubel Forsey click here.