10 Day Tourbillon
Ref. 5101P

With its rectangular Ref. 5101P “10 DAY TOURBILLON” men's wrist chronometer, the Geneva-based manufacture is taking the opportunity to demonstrate the virtuosity with which it masters sophisticated technical challenges. Never before has the world seen a manually wound tourbillon wristwatch with a power reserve of 10 days. With its sleek rectangular case, this masterpiece of mechanical timekeeping has everything it takes to become a cult object.
The Patek Philippe Ref. 5101P is the first timepiece that accommodates, in the confines of a wristwatch case, two complications which require a considerable amount of space: two mainspring barrels for a power reserve of 10 days and a tourbillon that compensates for the position error of the balance spring.
Patek Philippe’s manually wound caliber 28-20/220 was originally presented in a limited edition for the Ref. 5100 watch: It was the world’s first wrist chronometer with ten days’ power reserve, and it is still without peer. Now, Patek Philippe has gone a step further to present the first tourbillon wrist chronometer that only needs to be rewound once every ten days. The development and engineering work for the new 28-20/222 movement took three years, the better part of which was invested in the creation of a totally new tourbillon. To prevent the minute wheel or third wheel from obstructing the view of the tourbillon, the entire going train was relocated to the dial side. The tourbillon is now showcased on the bridge side as the dominant element. A look through the sapphire-crystal caseback affords a view of the plate with circular graining, the bridges with Geneva striping, six jewels secured in gold chatons, the mirror-polished tourbillon bridge, and the tourbillon cage which embraces the Gyromax balance wheel, one of the pioneering inventions to Patek Philippe's credit.
Like all Patek Philippe tourbillon wristwatches, the Ref. 5101P also comes with an official chronometer certificate issued by the C.O.S.C. as a guarantee of its extremely high rate accuracy. And as all other mechanical calibers crafted by Patek Philippe, its movement displays the Geneva Seal, recognized as the most prestigious official hallmark of impeccable craftsmanship. The Ref. 5101P is delivered with an exclusive certificate issued jointly by the Official Swiss Chronometer Bureau and the Geneva Seal Institute.
To provide a 10-day power reserve a most unusual feature for a wristwatch – the caliber 28-20/222 is equipped with two barrels whose size ratio was calculated to obtain the highest possible energy storage capacity. The two barrels are wound simultaneously. A coupling system with a slipping bridle spring on the first barrel prevents the mainsprings from being wound past their limit by disengaging the barrels as soon as they are fully wound. The power-reserve indication at 12 o'clock always informs the owner how long the movement will keep running before it has to be rewound.
The rectangular platinum case in the art déco style is over fifty millimeters long and truly befits the fascinating movement. It derives its elegance from the sleek three-tiered flanks, and thanks to its gentle curvature, it snugly hugs the wrist. The camber of the case is duplicated by the convex shape of the sapphire-crystal glass which is ground parallel on both sides to eliminate the magnifying-glass effect. It protects the satiny sheen of the 18K gold dial with the attractive “vintage rose” hue and the blackoxidized Breguet-style gold numerals, the subsidiary seconds dial at 6 o'clock, and the 10-day powerreserve scale at 12 o'clock. The company signature, the designation “Tourbillon”, and the serial number of the movement are inscribed on the dial. The caseback is also made of sapphire-crystal glass: it reveals the elaborately decorated movement. A discreet diamond positioned between the lugs at 6 o'clock indicates that the case of the Ref. 5101P is made of platinum. The watch is worn with a hand-stitched brown crocodile strap that is secured with a platinum prong buckle to match the case.
Because of the immense amount of work needed to craft it, the Ref. 5101P “10 DAY TOURBILLON” will always remain a rare timepiece. Only a few dozen of these watches are likely to be manufactured each year.