This JLC Master Ultra Thin replica puts a full perpetual calendar into a case that barely whispers on the wrist. Based on the Master Ultra Thin line, the 39mm stainless steel housing keeps the profile slim enough to slide under any shirt cuff without catching fabric. The black sunburst dial uses thin applied hour markers and dauphine hands, both finished in a polished silver tone that contrasts cleanly against the dark background. There is no plain date window on this dial. Jaeger-LeCoultre laid out a full perpetual calendar on the original reference, and this version follows the same four-register symmetry: day of the week at nine o’clock, date at three, month with the year indicator at six, moon phase at twelve.

Case & Movement Specs

• Case diameter: 39mm
• Case material: stainless steel with polished and brushed surfaces
• Dial: black sunburst with applied indices
• Crystal: sapphire with anti-reflective coating
• Hands: dauphine style, polished silver tone
• Movement: clone Cal. 868, automatic, 28,800 vph
• Power reserve: 40 hours (genuine Cal. 868: 43 hours)
• Water resistance: 50 m (same as genuine)
• Functions: hours, minutes and a perpetual calendar reading day of the week at 9, date at 3, month and year at 6, moon phase at 12

The Ultra Thin designation reflects the original caliber’s engineering priority: maximum thinness without sacrificing power reserve. On the wrist, you notice the case sits flat rather than doming upward, which keeps the overall stack height noticeably lower than most 39mm automatics.

Caliber Breakdown

Inside runs a clone of Cal. 868, automatic, beating at 28,800 vph and holding 40 hours of power reserve against 43 hours for the genuine Cal. 868. It drives the hours and minutes plus all four calendar indications, which makes the calendar, not the case, the most complicated part of this watch. The genuine watch behind it is the Jaeger-LeCoultre Master Ultra Thin Perpetual Calendar, sold on this site as the Master Ultra Thin 39mm Black Dial. Jaeger-LeCoultre’s 1000 Hours Control testing protocol, introduced in 1992, is what put the word Master on the dial in the first place. Compare this black-dial JLC super clone side by side with the white-dial Ultra Thin variant and the split is wider than the dial color: that one carries the same perpetual calendar in a pink gold case on a brown alligator strap, while this one stays steel on black, where the dark background makes the case appear even thinner because less light reflects off the dial surface. Both sit in the Master Control collection on this site, though both come from the Master Ultra Thin line, and they serve different wardrobe registers entirely.

How It Compares

Among 39mm dress watches, the Master Ultra Thin occupies a narrow lane between the austerity of a Patrimony and the sportiness of a Datejust. The black dial adds evening versatility that lighter versions cannot match. The calendar is the real difference from both of those references: a perpetual calendar works the 31, 30 and 28 day months out of the movement rather than out of the wearer, and on this dial it takes up four sub-registers instead of a single date aperture. If your rotation already includes a white or silver dial dress piece, this Master Ultra Thin super clone fills the gap for anything after sundown without duplicating what you already own.

Steel on black is the discreet way to carry a perpetual calendar, and the gold-cased versions of those same four registers are listed on the thin-case side of the JLC catalogue. Which of the three calendars to actually own is argued out in the perpetual calendars in our JLC buying guide.

Specifications

• Model: Jaeger-LeCoultre Master Ultra Thin Perpetual Calendar, 39 mm
• Reference: not marked on this listing, sold as Master Ultra Thin 39mm Black Dial
• Case: stainless steel, polished and brushed
• Case size: 39 mm
• Dial: black with applied hour markers and four calendar sub-registers
• Complications: perpetual calendar (day of the week at 9, date at 3, month and year at 6, moon phase at 12)
• Movement: clone Cal. 868, automatic, 28,800 vph
• Power reserve: 40 hours (genuine Cal. 868: 43 hours)
• Water resistance: 50 m (same as genuine)
• Crystal: sapphire
• Strap: black alligator with pin buckle