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Audemars Piguet Perpetual Calendar 25668
Audemars Piguet Perpetual Calendar 25668

Audemars Piguet has had a long and storied history with perpetual calendars. The illustrious Swiss watchmaking house created its first pocket watch with a perpetual calendar in 1923 and debuted its first perpetual calendar wristwatch in 1948. 

Perpetual calendars are some of the most revered complications in watch collecting circles, and Audemars Piguet makes some of the best out there. A particularly fascinating one is the Audemars Piguet Quantième Perpétual Automatique Squelette, also known as the Audemars Piguet Perpetual Calendar 25668. While this incredible timepiece was discontinued a while back, it is now a cherished collector’s item. Let’s find out more about this open-worked beauty.

What is a Perpetual Calendar? 

Why do we have leap years? Leap years exist because the true solar year is approximately 365.24 days, which is slightly longer than our typical 365-day a year calendar. Therefore, to make up for the variance, we add an extra day (February 29th) every four years. However, to complicate matters, adding the leap day makes the calendar longer. To recalibrate, leap years have to be omitted every so often and the next time a leap year will be skipped will be the year 2100.

Audemars Piguet Perpetual Calendar 25668
A perpetual calendar indicates the time, day, date, month, and moon phase

If we consider how our calendar is structured (where days of the month not only vary between 28 to 31 days, but every four years we also have to account for an extra day) we can start to appreciate how incredible a mechanical perpetual calendar watch is.

Perpetual calendar watches display the day, date, and month (and frequently the moon phases too) while keeping track of leap years. As a result, a perpetual calendar can indicate the correct date without the need for adjustments in perpetuity — well, at least until March 1, 2100. 

The Audemars Piguet Perpetual Calendar 25668

In 1978, at the height of the Quartz Crisis, Audemars Piguet audaciously launched an ultra-slim automatic perpetual calendar in the form of the Reference 5548. Many have credited this risky approach as having saved the company during an era where the quartz trend decimated the Swiss watch industry. Inside the AP Perpetual Calendar Reference 5548 was the super slim Caliber 2120/2800, which merged a Jaeger-LeCoultre base movement with a Dubois Dépraz perpetual calendar module. This movement proved to be a cornerstone of the AP Perpetual Calendar lineup and was used across 70 different references.   

Audemars Piguet Perpetual Calendar 25668
Audemars Piguet Caliber 2120/2800 self-winding movement

One of these references is Ref. 25668, also known as the Audemars Piguet Perpetual Calendar Automatic Skeleton, pictured here. These openworked Perpetual Calendar models were made from 1988 to 1993 specifically to show the beauty of the self-winding caliber inside the watch — from both the dial side and the caseback. The openwork design illustrates the incredible craftsmanship that goes into hand-finishing each movement, from engraving and beveling to polishing and flanking.  

Audemars Piguet only made 205 examples of the self-winding Perpetual Calendar ref. 25668, available in four different metals: 94 in yellow gold, 79 in platinum, 30 in pink gold, and two in white gold. Despite the complicated nature of the watch, the case of Reference 25668 measures a restrained and elegant 36mm in diameter and a mere 7.5mm thick. 

Audemars Piguet Perpetual Calendar 25668
Only 94 examples of the Perpetual Calendar ref. 25668 in yellow gold were ever made

The openworked (or skeletonized) dial of the Audemars Piguet Perpetual Calendar 25668 is beautifully designed, with four subdials that serve to display the perpetual calendar. There’s the date at 3 o’clock, the moon phases at 6 o’clock, the day at 9 o’clock, and the month at 12 o’clock, all of which float above the visible movement.

Made for the Fine Timepiece Connoisseur 

Though Audemars Piguet is best known today for its immensely popular Royal Oak watches, fine timepiece connoisseurs understand that the brand’s range of complicated watches is what distinguishes it as a high horology manufacturer.  

Flawlessly designed and built, the Audemars Piguet Quantième Perpétuel Automatique Squelette ref. 25668 is a rare and highly collectible watch for serious collectors. With a little over 200 examples ever made, those who have the privilege of owning an Audemars Piguet Perpetual Calendar 25668 are part of an exclusive club, indeed.

Written by

Celine Simon

Celine is a freelance luxury watch writer who has enjoyed working in the horology industry for over ten years. Like many of the high-end timepieces she writes about, she comes from Switzerland—the heart of fine watchmaking. From Singapore to Montreal to Geneva to Dubai, Celine has lived all over the world but now calls Southern California home.