SIHH 2011: Greubel Forsey Double Tourbillon 30 Technique
The Greubel Forsey Double Tourbillon 30° Technique is now available in a platinum case. The Double Tourbillon 30° functions include an hour and minute display, outer tourbillon (4-minute rotation), inner tourbillon (1-minute rotation) and a power reserve indicator. The movement features 385 parts, 43 jewels (olive-domed jewels in gold chatons) and an impressive 120-hour power reserve.
The large power reserve is a result of four fast-rotating power barrels (1 turn in 3.2 hours), one of which is equipped with a slipping spring to avoid excess tension. The barrels have a gold black chrome finished cover with relief engraving.
The balance spring has a Philips terminal curve with Geneva-style stud. It runs at 21,600 vph (3Hz). The balance wheel is variable-inertia, with white gold mean-time screws.
The main plates are made of nickel silver, and are frosted with polished beveling and a nickel-palladium finish. The bridges are also made of nickel silver and are frosted. The bridges are spotted with polished bevelling, with a nickel-palladium finish, and a gold nameplate bearing the individual number.
The case is made of 950 platinum with a convex sapphire crystal and a transparent back with a sapphire crystal. Case dimensions are 47.50 mm in diameter by 16.84 mm in thickness.
The hour and minute hands are in gold, with a black chrome finish. The small seconds and power reserve indicators are red triangles. A sapphire crystal is used for the 4-minute engraved indicator.
The crown is platinum with engraved and black lacquered GF logo. The strap is hand-sewn in black alligator leather, with a platinum 950 folding clasp, hand-engaved with the Greubel Forsey logo. Water-resistance is 30 meters (100 ft).
Source: Peter Chong