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To celebrate the 20th anniversary (2004-2024), Greubel Forsey presents its 10th Fundamental Invention: the Nano Foudroyante EWT. The mechanism’s energy is managed at the nanojoule scale, significantly reducing the number of components and the overall dimensions. The result is a 37.9mm 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.
Legacy of innovation
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. Thus, Greubel Forsey intro-duces its 10th invention: the Nano Foudroyante. This new Fundamental Invention is the most technologically disruptive—not only for Greubel Forsey but also for the universe of mechanical watchmaking.
Nanomechanics: a new horizon
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.
A revolutionized mechanism
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 3Hz 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 30μJ (microjoules) per jump, the Nano Foudroyante operates with only 16nJ (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.
It eliminates the entire gear train required in a traditional foudroyante 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 31mm in diameter within a 37.9mm case (the smallest ever built by Greubel Forsey).
Horology at its peak
There’s more: 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, an additional innovation: 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.
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 column-wheel control within the strong architectural design and exceptional finishing, a signature of Greubel Forsey.
A limited edition masterpiece
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.
The 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°C), tantalum requires rare expertise. The Atelier 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.
Nano Foudroyante EWT
Technical Specifications
| Hand-wound movement with 2 patents |
| Flying tourbillon with Nano Foudroyante, hours and minutes, small seconds, 60-second tourbillon rotation, 60-minute counter, Flyback function |
| 11 pieces Limited edition |
| MOVEMENT |
| NUMBER OF PARTS |
| Movement: 428 parts |
| Tourbillon cage: 142 parts |
| NUMBER OF JEWELS |
| 42 |
| Olived-domed jewels in gold chatons |
| CHRONOMETRIC POWER RESERVE |
| One full day, with chronograph engaged |
| FREQUENCY |
| 21’600 vibrations/hour |
| TOURBILLON |
| Flying Tourbillon with embedded Nano Foudroyante mechanism |
| Foudroyante dial, constant vertical indication |
| Titanium cage bridges, circlar-grained, polished bevelling, straight-grained flands with engraved GF logo |
| EXTERIOR |
| CASE |
| Tantalum and white gold with high domed synthetic sapphire crystal |
| Tantalum hand-polished bezel, transparent tantalum back |
| White gold caseband with hand-finished straight-graining |
| CASE DIMENSIONS |
| Diameter: 37,90mm |
| Height: 10,49mm |
| WATER RESISTANCE OF THE CASE |
| Water-resistant 3atm - 30m - 100ft |
| (standard NIHS 92-20/SN ISO 22810:2010) |
| DIAL SIDE |
| Multi-level in gold, rhodium-coloured, engraved and black lacquered hour-ring and minute-circle with a visual opening for the tourbillon |
| Small seconds and chronograph minutes counter in gold, polished bevel |
| Water resistance: 50m/5atm/160ft |
| Crown for winding and time-setting at 3 o’clock |
| Foudroyante, frosted, fractions of seconds engraved and black lacquered |
| STRAP AND CLASP |
| Non-animal material, hand-sewn |
| White gold pin buckle, hand-engraved GF logo |
