In 2009, the Manufacture introduced the Master Tourbillon with Calibre 978, which won the International Chronometry Prize organised by the Horological Museum of Le Locle, Switzerland. This calibre has been Jaeger-LeCoultre mainstay tourbillon movement ever since, and received a comprehensive update in 2019 featuring new high-end finishes. For the Master Ultra Thin Tourbillon Moon, Jaeger-LeCoultre’s engineers capitalised on the 978 movement to develop the new Calibre 983, with the addition of the moon phase and ‘jumping’ date complications.
Set in the upper half of the dial, the astronomical complication displays the Northern Hemisphere moon phases in the traditional way – a deep blue sky scattered with stars provides the background for a polished golden disc. Surrounding this is a ring with applied Southern Hemisphere moon phases on the left and the Age of the Moon on the right, each indicated by a double-ended hand. For the peripheral date display the Manufacture’s engineers chose Jaeger-LeCoultre’s signature ‘jumping’ complication. Every month, the date hand makes 90-degree jump, gliding rapidly from the 15th to the 16th, in order not to obscure the tourbillon.
The lower half of the dial is dominated by the tourbillon. A newly designed bridge in polished pink gold secures the titanium tourbillon cage (which weighs around 0.3 grams with its components) as it completes one revolution every 60 seconds. The fine tourbillon bridge and wide aperture maximise transparency and light, drawing the eye right through the mechanism.