Patek Philippe laid the foundation for its marque complication – the perpetual calendar chronograph – with the Reference 1518 in 1941. It followed this with the Reference 2499 that furthered the brand’s reputation for this combination of complications. The Reference 3970, coming more than years after the 1518, in 1984 carried on this tradition till 2004.

This example is from the fourth series of production and as such distinguished by several characteristics. In some cases, these characteristics were shared with the third series. The fourth series was produced between 1994 and 2004, bringing the Reference 3970 to a close.

Chief among these distinguishing characters is the use of faceted baton hour and minutes hands (instead of the feuille-style variety seen in the first and second series) as well as matching faceted large and small hour markers. In addition to these, the printing on the dial had a higher contrast quality to it, and the font used on the day and month wheels were noticeably sized up and were typically san serif, even if this last detail wasn’t a rule. However, the fourth series, of which 2,000 examples exist, typically came with matching deployant clasps, which this example also features. In addition, the movement and case numbers also mark this as one of the final series of the 3970. 

This 3970EP-027, made and sold in 1998, has a 36mm case with a rounded midcase that is home to the correctors for the calendar complication as well as the rounded pushers for the chronograph. The large knurled crown wears the Calatrava cross. The concave bezel is a classical detail while this example features an exhibition caseback topped with a removable, screwed on solid caseback. The long, straight lugs curve down sharply. They feature a subtle stepped detail. The top left lug features the precious metal hallmark on its outer flank. The watch comes on a leather strap secured by a signed deployant clasp in platinum. 

The dial by Stern Créations features a rare and coveted quality – it is semi-gloss with white gold faceted hour markers. The central chronograph seconds hand is platinum to match the case and for maximum contrast against the black dial. As was the case with the 3970, instead of a tachymeter scale is a simple seconds scale printed in white with Arabic numerals at five second intervals. 

The dial features two equisized registers at 9 and 3 o’clock – the former displays running seconds as well as the time on a 24 hour scale, while the latter shows 30 minutes of elapsed time and also integrates the leap year indicator. Both these registers are marginally sunken and are two-part in their construction. The twin windows at 12 o’clock display the day and the month. The register at 6 o’clock displays the date and also contains within it the moonphase crafted from sapphire glass. The elements converge to create an effect that is historically inspired but clearly made to high modern standards. 

Powering it is the manually wound Calibre CH 27-70 Q based on the Lemania calibre 2320, albeit without the swan neck regulator the èbauche featured. As is to be expected, the vertical clutch chronograph movement is mechanically robust and finished to Patek Philippe’s standards. It bears the Geneva seal which the brand was still using at this time before it transitioned to the Patek Philippe seal after 2009. 

This example is fresh from Patek Philippe service and comes with its Certificate of Origin (stamped Climo Jewellers S.A.S) and an Extract from the Archives - the latter confirming 1998 as the year of manufacture and sale, as well as the semi-glossy dial. This example from the final series of the 3970 is understated both in the combination of its elements and thanks to the classical proportions of the reference. This classicality is offset by its modern production and how it feels on the wrist. 

Closer look

Condition

This Patek Philippe Perpetual Calendar Chronograph 3970EP-027 is in very good overall condition. The case and lug proportions remain thick and well pronounced. The case was not polished during its most recent service with the manufacturer. Superficial and very light surface marks are found throughout the case and lugs. A more noticeable imperfection can be seen on the bezel between 9 and 10 o'clock and and on the midcase in the same position, though these remain mostly on the surface of the material. The semi-gloss dial shows light signs of age, though only under magnification. The movement is free from any signs of imperfections and has been well preserved. The watch was recently service by Patek Philippe in London. On the side of the lugs, the hallmarks remain visible and well-defined.

Warranty

The watch was recently serviced by Patek Philippe in January 2025 and thus comes with time remaining on the brand's servicing warranty. The watch also comes with a lifetime guarantee of authenticity from  A Collected Man.