Audemars Piguet

1990s Audemars Piguet Quantième Perpetual Calendar 18K YG (Ref. 25661BA) "Cal. 2120/2800"

Although Audemars Piguet may be best known for their Royal Oak series, notably designed by Gerald Genta, Audemars Piguet has a long lineage of interesting timepieces both before the conceptualization of the Royal Oak and after. Primarily consisting of unique chronographs, complex calendars, and charming dress models that were both stylistically and mechanically very ahead of their time.

Considering the climate of wristwatches in the late 1970s, at the height of the quartz crisis, the concept of designing and manufacturing a mechanically innovative watch was all but lost for most watch brands. Amidst this turmoil, Audemars Piguet seized an opportunity to create, in secret, one of the greatest achievements in horological history. 

Enter the Caliber 2120/2800 — an automatic winding, ultra-thin, perpetual calendar movement, measuring only a mere 3.95mm in height. This movement was based on the ultra-thin caliber 2120 created in 1967 and utilized in several iconic models such as the Royal Oak, Nautilus, and the 222, but was heavily modified to incorporate the perpetual calendar complication. This caliber was initially introduced in 1978 with the model 5548, the original Quantième Perpetual model, and was designed by the protege of Gerald Genta, Jaqulin Dimmer.

The Quantième Perpetual quickly evolved through the 80s and 90s, however each model was produced in very limited quantities. It’s known that 7219 cal. 2120/2800 movements were created over the 15-year production period of the movement.  

The Audemars Piguet Quantième Perpetual ref. 25661 was the first model to feature a sapphire crystal display case back, showcasing the exceptionally finished cal. 2120/2800 movement, and was produced from 1985 to 1994 in an extremely limited quantity of 342 pieces, 244 of which were in yellow gold.

Stock # APQP25661BA
Brand Audemars Piguet
Style Quantième Perpetual Calendar
Model 25661BA
Serial C8XXXX / No. 16X
Size Men's
Material 18K Yellow Gold
Dial White "Small Font"
Millimeters 36
Strap 2pc Handmade Leather Strap



The exceptional 18K yellow gold case exhibits only gentle signs of previous polishing while maintaining thick and symmetrical lugs, and deep hallmarks, with light signs of use present. The case retains its original unsigned crown. The sapphire case back is in excellent condition and displays the beautiful cal. 2120/2800 movement. The hallmarks and factory engravings remain extremely crisp and deep in the case back as well. The watch comes supplied on a 2pc handmade leather strap.


The original white "small font" dial featuring the characteristic sunken sub-dials is exceptionally well-preserved and in virtually flawless condition, exhibiting no damage or notable elements of age. The hands all remain original to the watch and are in excellent condition.


The watch is keeping time perfectly and functioning correctly. The service history is unknown. A movement service can be provided upon request.