Foudroyante, which is French for bolt of lightning), chronographs have always been very rare because in measuring fractions of a second by driving a hand that rotates every second uses a lot of energy.

And that’s a double whammy for the movement as the energy driving the fast-rotating foudroyante hand comes directly from the escapement where the slightest drop in torque can make a big difference to accuracy.

With the Nano Foudroyante: Greubel Forsey has solved the inherent drawbacks in foudroyante chronographs by using nanotechnology to reduce power consumption by an incredible 1,800 times.

And it’s worth noting that while the foudroyante rotates on top of the flying tourbillon, it’s dial is cleverly designed to continually have 12 o’clock at the top.

Combined that with a flying tourbillon and a very wearable 38 mm case – Greubel Forsey’s smallest case to date. I love the design, the complication, and the size. If I had a spare $600k this would be the Greubel Forsey for me.

From the press release

Greubel Forsey unveils the first official limited edition of its Nano Foudroyante: a breakthrough timepiece born from years of research, now matured beyond its Experimental Watch Technol­ogy (EWT) origins. Limited to just 22 timepieces, this creation marks a significant new chapter in Greubel Forsey’s 10th Fundamental Invention.

From prototype to timepiece

Originally presented in 2024 as a commemorative EWT edition, the Nano Foudroyante was Greubel Forsey’s most technically radical concept to date. Today, it has evolved into a fully realized and independent creation – no longer tethered to an anniversary or prototype designation.

The new Nano Foudroyante is crafted entirely in white gold, replacing the original combination of white gold and tantalum. It presents a different architectural identity: the gold dial is now finished in rhodium with a blue minute track, while the hands are rendered in blued steel with matching cannon pinions.

The foudroyante dial itself is now white with transferred numerals, enhancing legibility and echoing the crisp visual language of the tourbillon aperture. A blue textured rubber strap completes the aesthetic – a clear evolution from the original edition, and a declaration of this timepiece’s own distinct personality.

Nanomechanics: reinventing the possible

At the heart of this timepiece lies a disruptive idea: nanomechanics – the control of energy at the nanojoule scale inside a mechanical move­ment. This paradigm shift enables the Nano Foud­royante to operate its eponymous complication using just 16 nanojoules per jump, compared to 30 microjoules in traditional designs – a staggering reduction by a factor of 1,800.

The complication divides each second into six segments using a lightweight, red-treated hand that rotates once per second, driven directly by the oscillations of the 3Hz balance wheel. There is no traditional gear train; instead, a minimalist series of low-inertia wheels efficiently distrib­utes energy through the movement.

A compact and refined architecture

The Nano Foudroyante mechanism is embedded within Greubel Forsey’s first flying tourbillon, creating a visual and technical centerpiece. The foudroyante’s dial remains permanently oriented to twelve o’clock, even as the tourbillon rotates – ensuring optimal readability.

The timepiece features a hand-wound flyback with 2 patents, totaling 428 components (including 142 for the tourbillon cage). Despite this complexity, the movement measures just 31.60mm in diameter and fits within a 37.90mm white gold case – Greubel Forsey’s most compact ever.

The case is fitted with a high-domed sapphire crystal, straight-grained finishing on the caseband, and a transparent caseback. Subtle engravings – “Nano Foudroyante” and “Greubel Forsey” – stand out in polished relief over a hand-hammered background.

A new chapter, fully realised

This timepiece embodies maturity and intent, created for 22 collectors who will experience Greubel Forsey’s most energy-efficient, compact, and conceptually advanced timepiece to date.

For more information, please visit https://greubelforsey.com/en/watches/nano-foudroyante

Quick facts: Nano Foudroyante in white gold Limited Edition
Hand-wound chronograph movement with 2 patents
Flying tourbillon with Nano Foudroyante • hours and minutes • small seconds
• 60-second tourbillon rotation • chronograph seconds (trotteuse)
• 60-minute counter • flyback function
Movement
Dimensions: Diameter: 60 mm x Thickness: 40 mm
Number of parts

• Movement: 428 parts
• Tourbillon cage: 142 parts
• Weight of the cage: 835 g
  Number of jewels
• 53
• Olived-domed jewels in gold chatons

Chronometric power reserve

• One full day, with chronograph engaged

Barrel

• Fast rotating barrel (1 turn in 7 hours) with a fixed main spring bridle

Balance wheel

• Variable-inertia with gold mean-time screws (10 mm diameter)

Frequency

• 3 Hz/21’600 vibrations/hour

Balance spring

• Phillips terminal curve
• Geneva-style stud

Bridges and main plates

• Nickel silver, frosted and spotted with polished bevelling and countersinks, straight-grained flanks, nickel-palladium treatment
• Straight-grained and flat black polished steel chronograph mechanism, polished bevelling, straight-grained flanks
• Three-dimensional column wheel, frosted and circular-grained, polished columns
• Central seconds wheel, circular-grained, polished bevelling with relief-engraved texts
• Gold plate, circular-grained, with engraved limitation number

Tourbillon

• Flying Tourbillon with embedded Nano Foudroyante mechanism
• Foudroyante dial, constant vertical indication
• Titanium cage bridges, polished bevelling, straight-grained flanks, with engraved GF logo
• Platinum counterweight

Gearing

• Involute circle profile
• Micro-module with reduced play
  Displays
• Hours and minutes
• Small seconds
• 60-second tourbillon rotation
• Foudroyante, sixth of a second

Chronograph

• 60-second flange
• 60-minute counter, semi-instantaneous

Exterior
Case

• In white gold with high domed synthetic sapphire crystal
• Hand-polished bezel, caseband with hand-finished straight-graining
• Transparent back with high domed synthetic sapphire crystal
• Raised polished engraving “Nano Foudroyante” and “Greubel Forsey” on a hand-punched background
• Gold security screws

Case dimensions

• Caseband diameter: 90 mm
• Bezel diameter: 30 mm
• Case height: 49 mm
• Height on synthetic sapphire crystals: 34 mm

Water resistance

• Water-resistant 3 atm – 30 m – 100 ft (standard NIHS 92-20/SN ISO 22810:2010)

Crown and pushers

• Crown with pusher, in white gold, engraved GF logo
• Pusher in white gold, hand-polished

Dial

• Multi-level in gold, rhodium-coloured, minute-circle with blue finish, small seconds and chronograph minutes counter with polished bevel, engraved and lacquered indications, with a visual opening for the tourbillon

• Foudroyante in light alloy, polished bevel with flat black polished central

Hands

• Hours and minutes in polished blued steel with Super-LumiNova, hand-polished countersink, flat black polished head
• Small seconds and chronograph hands in polished blued steel, hand-polished countersink, flat black polished head
• Tourbillon and Foudroyante in light alloy, red treatment

Strap and clasp: Hand-sewn textured rubber, white gold pin buckle, hand-engraved GF logo

Price: 502’200 CHF (excluding taxes)

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