Baselworld 2010: Patek Philippe Ref. 5951P Split-Seconds Single Push-Piece Perpetual Calendar Chronograph

The centerpiece of the 2010 Patek collection? Patek Philippe's Split-Seconds Single Push-Piece Chronograph (Ref. 5950A) could have been the centerpiece of that company's line-up of watches at Baselworld 2010. But Basel 2010 is a very good year for Patek Philippine, rendering the Ref. 5960A as simply one of their more interesting releases. As amazing as the Ref. 5950A is, it is one-uped by its sibling, the Ref. 5951P.

Patek Philippe Ref. 5951P combines the split-seconds chronograph and single push-piece manipulation with a perpetual calendar feature. For those interested in the Split-Seconds Single Push-Piece Chronograph, we recommend you read out article on the Patek Philippe's Ref. 5950A. We will write about the Ref. 5951P in terms of how it varies from the 5950A.

The Ref. 5950A at the left, and the Ref. 5951P at the right.

Patek Philippe Ref. 5951P. Unlike the Ref. 5950A, which is made of steel, the Ref. 5951P's is made from precious metals, as one would expect from a Patek Philippe grand complication. Instead of the more classical look of the Ref. 5950A, the Ref. 5951P is given a more contemporary, art-deco-inspired case with a blue dial and red chronograph hands. To complete the look, the strap of the Ref. 5951P is even stitched with red thread.


Like the Ref. 5950A, which has the thinnest split second chronograph movement in the world, the Ref. 5951P has the the thinnest rattrapante chronograph with perpetual calendar ever crafted by Patek Philippe. The Caliber CHR 27-525 PS Q which powers the Ref. 5951P ihas a diameter of only 27.3 and an overall height of just 7.3 mm, just 2 mm thicker than the Caliber CHR 27-525 PS movement that powers the Ref. 5950A.

The 2 mm thicker movement adds an amazing set of features to this watch. The perpetual calendar display is located at the six o'clock position with the month and day being displayed in apertures over a sub-dial that displays the date. There are two circular apertures beside the sub-dial. One serves as a day night indicator while the other keeps track of leap years. A moon-phase display is in a curved aperture at 12 o’clock, and deviates from the true lunar cycle by only one day in 122 years.

Perpetual Calendar. Most watches with a date and month display has the date wheel or pointed set to move one day every 24 hours, and the month wheel or pointer set to move at the 31st of each month. Since not every month has 31 days, five times a year, you will have to correct the date. With perpetual calendars like the Ref. 5951P, when you set the watch, once you set the date, month and year the movement is designed so that in months with only 30 days, the month changes on the 30th and not the 31st, and the day hand will skip the 31st and go straight to the 1st. In February, the month changes to March on the 28th and not the 31st, and the day hand will skip the 29th, 30th and 31st and go straight to the 1st, except of a leap year. On a leap year the month changes to March on the 29th and not the 28th.

About Patek Philippe. Patek Philippe & Co. was founded in Switzerland in 1851. The companies emblem, the Calatrava Cross, was adopted by it at the end of the 19th Century. It is acknowledged as one of the finest, if not the finest, watchmaker in the world.