Master Ultra Thin Moon 39

The Master Ultra Thin Moon 39mm puts a genuinely thin automatic movement , 3.9mm, caliber 925/1 , under a moon phase display accurate to one day's drift per 1,000 years. That combination of mechanical thinness and astronomical precision is nearly impossible to find below $15,000. This is JLC doing what it actually does well: useful complications built with real craft, not marketing filler.

What it is

Jaeger-LeCoultre introduced this reference in 2016 in steel (Q1368470) and rose gold variants, with Q1368420 designating the steel case in silver dial configuration. The caliber 925/1 traces its architecture to the long-running 920 family, refined to 3.9mm total movement height. The 39mm diameter kept the proportions close to vintage JLC dresswatch tradition rather than chasing the 40mm+ trend of the era.

Production continues as of 2025 with minimal spec changes, which speaks to how settled the design is. Limited dial variations exist , sector dials and blue sunburst dials have appeared but the silver/steel combination in Q1368420 is the most traded reference.

Buying notes

The crystal sits very close to the dial on an ultra-thin case, so even minor bezel strikes can crack the sapphire without obvious external damage to the case. Check the moon phase disk carefully: the hand-painted or lacquered disk can show wear at the star cutouts if the watch was dropped or serviced carelessly. Case polishing is a real concern on these thin bezels , over-polished examples lose the crisp anglage and look anonymous.

Confirm the crown is seating fully; the 30m water resistance rating on 925/1 is marginal and a worn crown seal will push it below that quickly. Ask for service history: JLC movements in this price tier are sometimes left unserviced longer than they should be because owners assume dress watches run dry forever.

Market read

Steel Q1368420 trades in the $7,500 to $9,500 range in solid condition on the secondary market, well below the roughly $13,500 new retail. Rose gold variants command a significant premium and hold closer to retail. Polished or scratched cases sell at the low end of the steel range and can sit for months; unpolished examples with original bracelet or strap sell quickly.

The moon phase accuracy story resonates with informed buyers and has kept this reference from the steeper depreciation seen on simpler JLC three-handers.

Service expectations

Caliber 925/1 carries a JLC-recommended service interval of 8 to 10 years. A full service through an authorized center typically runs $600 to $900 depending on parts needed; independent specialists with JLC experience can do it for $400 to $600. The ultra-thin architecture means disassembly requires care , bring this to someone who knows thin-movement work, not a generalist shop.