10 Things to Know About the Patek Philippe Grandmaster Chime

This month marks Patek Philippe’s 175th anniversary. What better way to celebrate than with a series of limited-edition timepieces? Why not include the most complicated wristwatch Patek Philippe has ever created? That’s just what they did. Here are ten things you need to know about it.

1. This timepiece – the Grandmaster Chime, Ref. 5175, represents a remarkable effort. More than 100,000 hours over eight years were devoted to development, production, and assembly. The movement alone required 60,000 hours to perfect.  

2. The Grandmaster Chime is the first double-face wristwatch presented by Patek Philippe that can be worn with either dial facing up. The case, elaborately engraved in 18k rose gold, measures 47.4 mm in diameter and 16.1 mm in height. The central portion of the case rotates on an axis running from 12 to 6 o’clock. A patented reversing mechanism locks the case firmly in the desired position. The case contains 214 parts, and it required four years of development.  

3. The movement goes by the shorthand designation Caliber 300, but just as Prince Harry’s full title is His Royal Highness Prince Henry Charles Albert David of Wales, this movement’s full designation is Caliber 300 GS AL 36-750 QIS FUS IRM. It is the most complicated wristwatch movement Patek Philippe has ever produced.  

4. The manually wound movement has 20 complications and 1,366 parts, including 32 bridges and 108 jewels. It runs at the unusual frequency of 25,200 vph, or 3.5 Hz. A complete list of the complications is shown in the graphic linked. All of these complications are contained in a movement measuring only 37 mm x 10.7 mm. That is an amazing feat of micro-engineering.

6. In addition to the patented case-reverser system mentioned above, the movement contains five additional patented mechanisms:

• Alarm mechanism with time strike: this is a mechanism that acoustically indicates a preset alarm time with hour, quarter-hour, and minute strikes using the chiming mechanism of the minute repeater.
• Date repeater: this mechanism obtains date information from the perpetual calendar and forwards it to the repeating mechanism. Patek Philippe president Thierry Stern, who is a trained watchmaker, is the inventor.
• Isolation of the Grande Sonnerie in the “Silence“ mode: this mechanism uncouples the Grande Sonnerie from the movement when the “Silence” mode is selected, eliminating friction that consumes power.
• Selection of strikework operating mode: this mechanism allows the automatic time strike to be selected or disabled with a single slide switch: Grande Sonnerie, Petite Sonnerie or Silence. Formerly, two separate switches were needed to make these settings.
• Unique four-digit year display: this mechanism automatically synchronizes the four-digit year display with the leap-year cycle and allows convenient correction of both displays in either direction.

7. The first two patents listed above – the alarm with time strike and the date repeater – are entirely original complications. They were unknown to watchmaking prior to the creation of this watch.

8. This is the first Patek Philippe wristwatch with both grand and petite sonneries. The grand sonnerie is often cited as the most difficult complication in watchmaking. The Ref. 5175 grand sonnerie automatically chimes the hours and quarters on three gongs. At the top of each hour, it sounds the corresponding number with low-pitched tones.

At each quarter, it signals first the hours, then the number of quarters, indicated by triple strikes on three gongs, with each quarter having its own melody. When the grande sonnerie is not required, the slider located at 9 o’clock can be used to set the watch to “petite sonnerie”, or to “silent.” The sonneries, and the minute repeater, require their own twin-barrel mechanism that provides a 30-hour power reserve.  

9. The Grandmaster Chime features an instantaneous perpetual calendar, meaning that all of the calendar displays change at the same time, instantly. Most perpetual calendar displays, which are less complete and much less complex, do not change instantly, and some require more than an hour to change.

10. The Ref. 5175 Grandmaster Chime will be produced in a limited edition of seven pieces, one of which will be displayed in the Patek Philippe Museum in Geneva. The other six are spoken for. They have been reserved by longstanding Patek Philippe collectors, at the estimated price of 2.5 million CHF.