The ladies' chronograph presented by Patek Philippe for 2018 is one of just three references for ladies out of a total of 14 new watches in the collection this year. It replaces the Ref. 7071, which was the brand's first ladies' chronograph, launched in 2009, and is still the only ladies’ chronograph in the Patek Philippe collection. The original model was presented in a cushion-shaped case and marked the introduction of Patek Philippe's first in-house manual chronograph movement, the CH 29-535 PS, to replace the venerable Lemania CH 27-70 calibre that the company had been using in its chronographs for a couple of decades. This movement has a column wheel and horizontal clutch and introduced six patented innovations [see below].
The new chronograph comes in a 38mm diameter round case in 18-carat rose gold with some discreet touches that set it apart as a timepiece of distinction. The angular lugs, for example, give the watch a harmonious symmetry, but they are also fiendishly difficult to polish. The hand-engine turned decoration on the gold chronograph pushers is also testament to the attention to detail of Sandrine Stern, Patek Philippe's Head of Creation.
Typical of Patek Philippe, the silvered opaline dial is the epitome of classic design and legibility, with applied Breguet numerals inside a pulsometer scale that is clearly separated from the outer seconds graduations. The "bi-compax" chronograph arrangement includes a small-seconds subdial at 9 o'clock and an instantaneous 30-minute totaliser at 3 o'clock. A glass-box style sapphire crystal enhances the legibility, making the watch look bigger than it actually is. The same glass-box style of crystal is used for the transparent case back, offering an excellent view of the movement and its meticulous hand finishing, unobstructed by a winding rotor.
For the ultimate touch of luxury, the bezel is set with 72 diamonds (approx. 0.78 carats) and a further 27 diamonds (approx. 0.21 carats) are used to set the gold prong buckle used to fasten the alligator leather strap, bringing the total diamond weight to just under one carat (approx. 0.99 carats).
The Patek Philippe Ref. 7150/250R-001 offers a power reserve of at least 65 hours when fully wound if the chronograph is not used and retails for 74,000 Swiss francs.
The six patents in calibre CH 29-535 PS
1) Optimized tooth profile
The wheels of the chronograph mechanism feature an exclusive patented tooth profile that eliminates the risk of the hands jumping in either direction, increases energy transmission efficiency and reduces friction.
2) Improved penetration adjustment between the clutch and the chronograph wheel
The adjustment between the teeth of the clutch wheel and the teeth of the chronograph wheel is governed by a large eccentric column wheel cap, working directly with the tip of the clutch lever instead of the conventional eccentric placed next to the clutch wheel. This ensures more precise adjustment of the penetration between the clutch and the chronograph wheel.
3) Improved synchronization between the clutch lever and the blocking lever
The clutch lever is fitted with a finger piece that directly synchronizes both the clutch lever and the blocking lever (usually done via the column wheel). This means that the watchmaker only has to adjust one point instead of two and also avoids jumps by the chronograph hand.
4) Pierced-out minute-counter cam
A new minute-counter cam with a slot prevents abrupt blocking when the chronograph is reset.
5) Self-setting return to zero hammers
The reset hammers are equipped with a self-setting system that removes the need for mechanically adjusting the minute hammer function, thus increasing the reliability of the mechanism.
6) Hammers pivoted between jewels
There are separate jewelled bearings on the same axis for the seconds and minutes hammers. Each hammer is pressed against its respective heart cam by its own spring. This system ensures that the hammers remain precisely vertically aligned and improves the smoothness of their rotation.
