Limited Edition of 11 Pieces Exclusive to the U.S. Market
In their search for ultimate precision, in 1999 Robert Greubel and Stephen Forsey commenced work on a creation that reinterprets the tourbillon while improving timekeeping. 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 blue ceramic, an extraordinarily accurate timepiece that is both refined and robust.
Unparalleled accuracy
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.
The ceramic case: robustness and radiance
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%. 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 satinfinishing, 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.
Technical Specifications:
The case, in blue ceramic, has a caseback, bezel and caseband machined from a block of ceramic, polished and straight grained, hand-finished. Three-dimensional, variable geometry-shaped lugs. It measures 48.4mm x 17.7mm. It has double sapphire crystals and it is water resistant to 30 meters.
Movement is the Swiss manual-wind Greubel Forsey caliber Double Tourbillon 30° with 43 jewels, 21,600 vph and a power reserve of 120 hours. Synthetic sapphire bridges. Olived-domed jewels in gold chatons. 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. 22kt gold cover with nickel-palladium treatment and relief engraving. Variable-inertia balance wheel with white gold mean-time screws. Balance spring: Phillips terminal curve with Geneva-style stud.
Main plates: nickel silver, frosted with polished bevelling 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. Gearing: involute circle profile. Conical gearing with profiled teeth. Functions are:hours and minutes, small seconds. Outer tourbillon 4-minutes rotation. Inner tourbillon 60-seconds. Power-reserve indicator
The ‘dial” is a nulti-level synthetic sapphire hour-ring, galvanic growth hour indeces, 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 SuperLuminova. Small seconds, power-reserve (red triangles). Engraved synthetic sapphire 4-minutes indicator.
It comes on a blue rubber strap with a titanium folding clasp.
