Patek Philippe’s reference 3970 evolved from a line of important and iconic perpetual calendar chronograph wristwatches, which first began in 1941 with the reference 1518. Launched in 1986 as the replacement for the reference 2499, the 3970 featured a heavily modified Lemania-based movement over the Valjoux-based calibers used in the earlier 1518 and 2499 references. Both models shared pump pushers and down turned stepped lugs, however the 3970 used a 36mm case with a decidedly modern appeal.

The reference was divided into three series: the first series featured a snap on caseback, with applied gold baton indexes and feuille hands. The second series, like the present watch, still used feuille hands but featured a screw-down, solid caseback, with the hallmarks stamped on the outside of the lugs. The third series would use baton hands, and a sapphire display back, along with including a second, screw-down solid caseback. The letter E in 3970E represents "étanche" or "water-resistant". The inside case back is furthermore engraved with the reference number and the case number.

The present, second series 3970E is fresh-to-the-market, and is remarkably well-preserved. The case, in our opinion, remains unpolished with strong fluting to the lugs, and crisp gold hallmarks on the lugs and case back. Highly sought after, this perpetual calendar chronograph from 1990 also has a flawless dial which is sure to appeal to the most discerning connoisseurs. The reference 3970E has become highly sought after, and this lovely example will impress collectors seeking a superb example of Patek Philippe’s iconic perpetual calendar chronograph models.