Jaeger-Lecoultre Q6042521 Duometre Quantieme Lunaire

The Watch: The Jaeger-LeCoultre Duomètre à Quantième Lunaire Ref. Q6042521 is a technical and aesthetic marvel, showcasing JLC’s groundbreaking Dual-Wing architecture in a refined 40.5mm rose gold case. First introduced at SIHH 2012, this watch reimagined the original 42mm Duomètre with a more wearable size.

The dial is a display of complications and artistry. Featuring a photorealistic moonphase with an age-of-the-moon indicator at 10 o’clock, paired with a radial date display, the watch delivers both beauty and practicality. The off-centered time display at 2 o’clock uses appliqué numerals and rose gold Delta hands, while a 1/6th-of-a-second jumping seconds hand at 6 o’clock adds dynamic motion. The dual power reserve indicators balance the layout, highlighting the watch’s twin-barrel system—one barrel powers the timekeeping, while the other handles the complications, ensuring no loss of amplitude or precision.

Powering the watch is the manually wound Caliber 381, a technical tour de force with 50 hours of power reserve per barrel. Its dual drivetrain ensures chronometer-grade accuracy, while the zero-reset mechanism allows the watch to be set precisely to the second—or even 1/6th of a second. The movement is visible through the sapphire caseback, showcasing a German silver mainplate, black-polished steel components, and a radiant côtes de soleil finish emanating from the balance wheel.