The Master Ultra Thin collection epitomizes Jaeger-LeCoultre’s philosophy of watchmaking, uniting timeless beauty with mechanical virtuosity to create the quintessential dress watch for the modern aesthete. In 2023, the collection is enriched by a new interpretation of the Master Ultra Thin Power Reserve, featuring a subtly modernized case and dial design, a new gradient midnight blue sunray dial, and a significantly increased power reserve.
Jaeger-LeCoultre Calibre 938 Revised to Provide a 70-Hour Power Reserve
In line with La Grande Maison’s pursuit of timekeeping precision, together with added utility for the user, the Manufacture constantly improves its in-house calibers in line with advancing technology. Caliber 938 has been significantly revised to power a new generation of timepieces. Most notably, the power reserve has been increased to 70 hours – long enough to leave the watch aside for an entire weekend and wear it again on Monday with no need to rewind it or reset the time.
This significant gain in power reserve has been achieved without adding to the size of the caliber, which remains 4.9 mm thick. The mainspring barrel was redesigned, some key components are now made of silicon, which makes energy transmission smoother by reducing friction of the moving parts, and other minor changes have been made to bring greater reliability.
The power reserve function is a signature complication of Jaeger-LeCoultre, pioneered by the Manufacture in 1948 with the introduction of Caliber 481. The Powermatic, recognized by its distinctive red-and-white indicator, was the world’s first self-winding timepiece with a power reserve gauge and quickly became a key model for the Manufacture in the early 1950s. The Master Ultra Thin Power Reserve is equally recognizable, with the distinctive design of the power reserve display complemented by date and small seconds indicators – the three complications bearing witness to the complexity of the caliber and the technical savoir-faire of Jaeger-LeCoultre’s watchmakers.
A Sophisticated Aesthetic Update and a Beautiful Midnight Blue Dial
While the size of the case remains the same as the preceding version of the Master Ultra Thin Power Reserve – retaining the elegant 39 mm diameter and 8.95 mm thickness – its design has been subtly modernized, with revised proportions and slimmer, more elongated lugs that make it even more comfortable on the wrist.
The dial architecture has also been refined. While retaining all the symmetry and balance of the earlier dial layout, larger sub-dials highlight the complications, making the date, power reserve and small seconds displays even more legible than before, while giving the dial a more integrated overall appearance. This is amplified by the newly elongated shape of the applied hour markers, and the use of a different finish (polished and satin) on each facet of the Dauphine hands, and the use of transferred golden dots to mark the minutes track. Matching the color of the pink gold case, these elements create aesthetic harmony while contrasting dramatically with the gradient midnight blue of the sunray dial. The subtle matt texture of the sub-dials adds visual depth and richness.
Adding a final flourish, the new Master Ultra Thin Power Reserve is presented on a navy-blue alligator strap. Straps and buckles can be very easily interchanged as the wearer wishes – adding even more versatility to this sophisticated, modern timepiece.
Technical Specifications
Model: Master Ultra Thin Power Reserve
Case: Pink Gold 750/1000 (18 carats)
Dimensions: 39 mm diameter x 8.95 mm thick
Calibre: Jaeger-LeCoultre Automatic Calibre 938
Functions: Hours, minutes, small seconds, date, power reserve indicator
Power Reserve: 70 hours
Dial: Gradient blue sunrayed
Water resistance: 5 bar
Strap: Blue alligator
Reference: Q137258J
Photos by Jaeger-LeCoultre.
