Q: Is there a time when correcting the calendar on a watch will break it?
I heard that there is a time when correcting the calendar causes the clock to break, but is that really true?
2025/9/23 update
A: Some models require attention between 8 PM and 4 AM
Many mechanical watches with calendar displays that allow fast forwarding have a time period during which they will break if the calendar is advanced quickly: between 8 PM and 4 AM (this period may vary depending on the model, but it is usually between these times).
If you wish to correct the date display during this time, use the crown to advance the hour hand beyond the above hours, then fast-forward the calendar. In this case, fast-forward the calendar only up to one day, and then adjust it by advancing the hour and minute hands. This is because the numbers printed on the date display disc may not line up neatly with the center of the window frame if you fast-forward the date. However, some mechanical calendars, which do not change the date instantly, do not have a time period during which the date cannot be corrected.
Additionally, movements that can set the date backward generally do not have any time periods during which the date cannot be adjusted. Examples of such movements include the Cal. 9S86 used in Rolex GMT models and Grand Seiko GMT models, and the Cal. 01 used in Breitling.
Cal. 01, announced by Breitling in 2009, is a movement developed in-house over five years. It is renowned for its modular structure, which allows for easy expansion and maintenance. The calendar's fast-forward date function is designed to operate 24 hours a day without damaging the movement. Automatic winding (Cal. 01). 47 jewels. 28,800 vph. Power reserve of approximately 70 hours. Stainless steel case (diameter 41mm, thickness 13.6mm). Water resistant to 10 bar. Price: 1,463,000 yen (tax included). (Inquiries) Breitling Japan Tel. 0120-105-707
This June 2025 model features the Cal. B31 automatic movement, which has no blackout period for date adjustment. The development concept for the Cal. B31 was based on the Cal. 01 chronograph movement used in the Navitimer, but with a focus on time display, while improving practicality and reliability. It underwent 100,000 crown windings, 3,456,000 rotor windings, and 60,000 500G shock tests. Reflecting this rigor, this watch comes with a five-year warranty. It is also COSC-certified by the Swiss Official Chronometer Testing Institute, ensuring high practical precision and ensuring a watch that will leave you satisfied. Automatic (Cal. B31). 28,800 vph. Power reserve: approximately 78 hours. Stainless steel case (44mm diameter). Water resistant to 200m. Price: ¥1,177,000 (tax included). For inquiries, please contact Breitling Japan at 0120-105-707.
This watch is powered by the in-house automatic movement, Cal. EMP01, manufactured by Péquigner, a French manufacturer dedicated to reviving the French watchmaking tradition. It's based on the Royal Origin Quatre Fonction. As the "fonction" in the name suggests, the watch features a day-date display with no blackout periods, a small seconds hand, a power reserve indicator, and a moon phase display. The Cal. EMP01's unique design allows for a wide range of functions to be added or removed, including models with a GMT display and limited functionality. This watch also features a sapphire crystal dial, through which the Cal. EMP01 can be seen. Automatic movement (Cal. EPM01). 39 jewels. 21,600 vph. Approximately 88 hours of power reserve. Stainless steel case (42mm diameter, 12.3mm thick). Water resistant to 50m. Price: ¥2,255,000 (tax included). (Inquiries) Calibre Vingt-et-Un Tel. 03-6206-2333
