Patek Philippe 3970E Perpetual Chronograph 18K YG "BIG HALLMARKS" 2nd Series RARE

This Patek Philippe reference 3970E is a second-series example of the watch that carried Patek Philippe's perpetual calendar chronograph into the modern era, distinguished by the bold 750 gold hallmark struck on the outer flank of the lug, a detail that rewards the collector who reads a case as closely as a dial. Conceived to succeed the fabled 2499, the 3970 stands among the defining watches of Philippe Stern's stewardship, and its restraint was a quiet act of confidence: where the 2499 wore 37.5mm, Stern shrank the case to 36mm, staking the firm's prowess on the harder feat of housing immense complication in a smaller frame. Manually wound, it runs the calibre CH 27-70 Q, the first chronograph movement Patek built outside the Valjoux tradition, drawn instead from the revered Lemania 2310 ébauche and then regulated and finished to a standard that rivals anything of its period, here carrying a perpetual calendar and moon phases across a silver dial. The three-piece yellow gold case measures 36mm in diameter and 12.9mm thick, its screw-down back announcing the Étanche evolution that gives the E-series its name, and it carries its complication with unusual discretion on the wrist. A complication Patek invented and still commands, the perpetual calendar chronograph finds in the 3970E its most lionized modern statement.