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2007 Double Tourbillon 30 Degree Secret

2007 Double Tourbillon 30 Degree Secret
A well-guarded secret

When introducing their Double Tourbillon 30° at BaselWorld 2004, Inventor Watchmakers Robert Greubel and Stephen Forsey had defined an architectural approach focusing on the visibility of their invention, so as to ensure complete visual access to the double cage and its incredible mechanical choreography.

Dedicated to connoisseurs of Haute Horlogerie with a preference for discretion and for whom observing the mechanism is an intensely personal pleasure, the Double Tourbillon 30° now appears in a less extrovert and one might almost say ‘secretive’ style, even though such a splendid dial naturally hints at the treasure it is guarding.

This exquisitely crafted matt-finished gold dial suggests the presence of an exceptional mechanism, thanks to its unusual and particularly wide subdial at 6 o’clock with a slender blued steel hand testifying to the four-minute rotation of the outer cage of the Double Tourbillon 30°.

The power-reserve is displayed on a sector indicating the full 72 hours of perfect operation provided by rapid-rotating twin barrels. Issued in a strictly limited edition of 11, the Double Tourbillon 30° “Secret” comes in a white gold case that is entirely polished, apart from the centre band of the case which is delicately straight-grained by hand.

Fortunately however, the secret of this Double Tourbillon 30° is not impenetrable and, although hidden from view on the wrist, the choreographic performance of the cages may nonetheless be admired through the case-back protected by a domed sapphire crystal. The 128 parts making up the first fundamental Greubel Forsey invention weigh a total of 1.17 grams, enabling the variable-inertia balance to oscillate to and fro three times a second, whereas its rotation axis shifts constantly due to the relative speeds of the cages and the 30° angle that links them together.

Greubel Forsey Watch

Technical Specifications

Double Tourbillon 30°– Secret
Mechanical hand-wound movement, GF Calibre 02j
Double Tourbillon 30°, Outer Tourbillon 4-minute rotation indicator, Inner Tourbillon 60-second rotation indicator,
power-reserve indicator. Patented DT30° mechanism

Limited edition of 11 pieces

Movement

Movement dimensions
• Diameter: 36.4 mm
• Thickness: 9.65 mm

Number of parts
• Complete movement: 304 parts
• Tourbillon cage: 128 parts
• Weight of the cage: 1.17 g

Number of jewels 39
Olive-domed jewels in gold chatons

Power reserve 72 hours

Barrels Rapid rotating twin barrels (1 Turn in 3.2 hours) one of which equipped with a slipping spring so as to avoid excess tension

Balance wheel Free sprung balance with white gold mean-time screws (10mm diameter)

Frequency 21’600 vibrations/hour

Balance spring
• Phillips terminal curve
• Geneva-style stud

Main Plates: In nickel silver with fine circular graining centred around the Tourbillon, finished in “jade gold”

Bridges Hand-Frosted nickel silver, finished in «jade gold»

Gearing • Involute circle profile
• Conical gearing with corrected profile

Inner Tourbillon

• Inclined at a 30° angle, 1 rotation per minute
Outer Tourbillon

• 1 rotation in 4 minutes
• Hand-bevelled and openworked cage pillars
• Solid gold counterweight

Displays

• Hours and minutes
• Small second
• 4-minute Outer Tourbillon rotation indicator
• 72-hour power reserve on a sector

Habillage

Case

• Gold with convex sapphire crystal. Limited edition of 11 pieces
• Transparent back with convex sapphire crystal
• Raised engraving of the name of the invention on a hand-punched background
• Gold security screws
• Polished bezel, centre band with hand-finished straight graining
• 3 dimensional, variable geometry-shaped lugs
• Hand-engraved individual number

Case dimensions

• Diameter: 43.5 mm
• Thickness: 15.84 mm
Water resistance of the case 3 ATM – 30 m – 100 ft
Crown Gold with engraved and black lacquered GF logo

Dial • Two-part gold dial
• Silvered finish
• Gold appliques
• Gold small seconds and power-reserve sectors
• Gold Plate with individual number
• Applied gold logo

Hands Hours and minutes, small seconds, power-reserve and 4-minute indicator in flame-blued polished steel

Strap Hand-sewn black or brown alligator leather with gold folding clasp, hand-embossed with the Greubel Forsey initials