Greubel Forsey Double Tourbillon 30° Technique in Ceramic

The Double Tourbillon 30°, the first Fundamental Invention by Greubel Forsey, was presented in a timepiece at Baselworld in 2004. This proved a success for the independent Atelier, and seven years later, the Double Tourbillon 30° Technique won first prize at the Concours International de Chronométrie. The timepiece achieved a record score of 915 points out of 1000 with an average timing rate of between 0.3 and 0.8 seconds per day across the whole competition.

Now Greubel Forsey is presenting the Double Tourbillon 30° Technique in ceramic, an extraordinarily accurate timepiece that is both refined and robust.

The Double Tourbillon 30° at the heart of the timepiece contributes to its exceptional accuracy. Inside a cage which rotates in four minutes, a smaller cage containing the balance and spring assembly is inclined at an angle of 30° relative to the first cage and completes a revolution in 60 seconds. The combination of the 30° inclination with the different rotational speeds of the two tourbillons improves timekeeping by averaging out positional errors due to gravity in all usual wristwatch positions and especially in stable positions.

In the Double Tourbillon 30° Technique, four coaxial barrels coupled to a spherical power-reserve differential, provide a chronometric power reserve of 120 hours.

Inspired by the phenomena of transparency and light, Robert Greubel and Stephen Forsey are pushing back the boundaries of horological architecture to draw the beholder deep inside an emblematic Greubel Forsey timepiece. For the first time encased in ceramic – a highly rigid material – this limited edition of 11 timepieces is made available to the US market.

The shades of the impressively finished and detailed blue ceramic case play with the light flooding through into the sapphire crystal movement. The timepiece has been reconstructed to incorporate these elements, requiring a very particular expertise and know-how. It now reveals the captivating spectacle of the two completely suspended cages of the Double Tourbillon 30° mechanism.

Transparency has always been an integral part of Greubel Forsey creations, and this proves particularly evident in the construction of the various editions of the Double Tourbillon 30° Technique – all presenting a panoptic view of the movement’s architecture. This Double Tourbillon 30° Technique in ceramic pushes back the boundaries of transparency even further by revisiting the construction of the entire timepiece to work with the specific constraints of sapphire crystal.

The eye can distinguish each element in marvellous detail. The small seconds and power reserve indicators in gold are finished in blue to present a contrasting effect against the frosted main plates and recall the glistening blue ceramic.

The hour and minute ring, as well as the 4-minute tourbillon-rotation indicator at 6 o’clock are both Immersive architecture made from sapphire to let the light into all levels of the mechanism. The hands are open-worked to further enhance the sense of light and transparency. Seemingly suspended in mid-air in a mystical dance, the Double Tourbillon 30° immediately attracts the attention of the viewer.

Having reconstructed the movement, Robert Greubel and Stephen Forsey embraced the challenge of accommodating sapphire crystal elements, particularly complex to machine in three dimensions and to finish to achieve the unique geometry and exacting standards of a Greubel Forsey timepiece.

The two creator watchmakers took the movement to the architectural extreme, creating three-dimensional sapphire bridges that proved particularly challenging to realise. Machined from single blocks of sapphire, their flanks are polished using different grains, requiring highly specialised tools, exceptional precision and expertise. The bevelled angles reveal a matt finish that magnificently contrasts with the polished transparent surfaces of the sapphire.

Thanks to this transparency, the entirety of the wheels and pinions comprising the timepiece are laid bare to reveal unprecedented visual access to the movement architecture.

On the dial side, the tourbillon bridge, barrel bridge, differential bridge and power-reserve bridge have been removed and recreated in sapphire to showcase the timepiece’s inner mechanism. In order to incorporate these new elements, the movement had to be rethought. Even the restrictions imposed by screws were taken into consideration in this spirit of creation: The bridges are specially mounted to absorb shocks to which the sapphire could be subjected. The plates, bridges and the mechanical architecture are therefore entirely new.

On the caseback side, the three-dimensional gear train bridge reveals an unobstructed view of the magnificently finished architecture beneath. This unusually large bridge features a multi-level design with countersinks that allow the wheels to precisely imbricate with the sapphire. The entire mechanism radiates light to reward the beholder with an enchanting spectacle. The lower tourbillon bridge – also made from sapphire – exactly reproduces the steel bridge that originally adorned the Double Tourbillon 30° Technique, marking a major feat in sapphire workmanship.

This is the first time that Greubel Forsey showcases a movement inside a ceramic case, the making of which requires great precision. The material is compacted by pressing and shaped before firing, where a thermal process shrinks it by around 25%.

Ultimately, the case measures 48.40 mm in diameter and 17.77 mm in height. Once the elements have been sintered at a very high temperature, the ceramic solidifies, making the case extremely hard and therefore more difficult to work with. The material becomes extremely resistant to scratches and corrosion, meaning the finishing requires exceptional know-how.

From polishing to linear or circular satin finishing, the finishes refine the contours of the timepiece, perfecting it in the true Greubel Forsey spirit. The deep blue ceramic gives the Double Tourbillon 30° Technique a subtle shimmer, while its physical properties make it extremely resistant. Myriad colours, finishes and textures play across the blue ceramic case and the sapphire movement.

This iconic timepiece in blue ceramic with its new architecture is being released as a unique edition of 11 timepieces exclusively available to the US market.

It is supplied with a blue rubber strap, complete with a titanium folding clasp decorated with a hand-engraved Greubel Forsey logo. The crown – also in ceramic – features a tone-on-tone engraved Greubel Forsey logo.

Technical details

Model: Double Tourbillon 30° Technique Ceramic

Movement

Hand-wound movement with synthetic sapphire bridges
Patented tourbillon
Double Tourbillon 30° • hours and minutes • small seconds • outer tourbillon 4-minutes rotation • inner tourbillon 60-seconds • power-reserve

Movement dimensions
• Diameter: 38.40 mm
• Thickness: 12.15 mm

Number of parts
• Movement: 421 parts
• Two tourbillon cages: 132 parts
• Weight of the two cages: 1.17 g

Number of jewels
• 43
• Olived-domed jewels in gold chatons

Chronometric power reserve
• 120 hours

Barrels
• Four coaxial series-coupled fast-rotating barrels (1 turn in 3.2 hours), one of which is equipped with a slipping spring to avoid excess tension
• 22k gold cover with nickel-palladium treatment and relief engraving

Balance wheel
• Variable-inertia with white gold mean-time screws (10.70 mm diameter)

Frequency
• 21’600 vibrations/hour

Balance spring
• Phillips terminal curve
• Geneva-style stud

Main plates
• Nickel silver, frosted with polished beveling and countersinks, straight-grained flanks, nickel-palladium treatment

Bridges
• Synthetic sapphire crystal, polished flanks
• Nickel silver, frosted and spotted with polished bevelling and countersinks, straight-grained flanks, nickel-palladium treatment
• Gold plate engraved with the individual number

Inner tourbillon
• Inclined at a 30° angle, 1 rotation per minute

Outer tourbillon
• 1 rotation in 4 minutes
• Hand-bevelled and open-worked cage pillars
• Gold counterweight

Gearing
• Involute circle profile
• Conical gearing with profiled teeth

Displays
Hours and minutes
Small seconds
120-hours power reserve on a sector
4-minutes outer tourbillon rotation
60-seconds inner tourbillon rotation

Case
Ceramic
Diameter: 48.40 mm
Height: 17.77 mm
Caseback, bezel and caseband machined from a block of ceramic, polished and straight grained, hand-finished
Three-dimensional, variable geometry-shaped lugs
Engraving “Double Tourbillon 30°” and “Greubel Forsey”
Engraved individual number
Water-resistant 3 atm – 30 m – 100 ft (standard NIHS 92-20/SN ISO 22810:2010)
Crown: Ceramic with engraved GF logo

Dial
Multi-level synthetic sapphire hour-ring, galvanic growth hour indexes, engraved and lacquered inner tourbillon rotation indicator
Small seconds and power-reserve indicators in gold, blue finish

Hands
Hours and minutes in polished gold, with Super-LumiNova
Small seconds, power-reserve (red triangles)
Engraved synthetic sapphire 4-minutes indicator

Strap and clasp
Rubber
Titanium folding clasp, engraved with the GF logo

Edition
Limited edition of 11 pieces

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