The JLC Geophysic True Second 8018120 clone belongs to Geophysic, which is a Jaeger-LeCoultre collection in its own right and not a branch of Master Control; the name goes back to the 1958 Geophysic built for the International Geophysical Year. The dial states it outright, with GEOPHYSIC TRUE SECOND printed above the six and nothing else beyond the signature. The True Second complication means the seconds hand jumps once per second in precise increments rather than sweeping continuously, creating a visual rhythm that separates this piece from every other watch in the Master Control catalog. At 39.6mm in stainless steel, the case sits slightly larger than the standard 39mm Ultra Thin models. The dial uses a clean layout with minimal text, letting the jumping seconds hand serve as the defining visual element.

Build Details

• Case diameter: 39.6mm
• Case material: stainless steel
• Reference: 8018120
• Dial: silver-white with applied hour markers
• Crystal: sapphire, domed
• Movement: clone Cal. 770, automatic, 28,800 vph, deadbeat seconds
• Functions: hours, minutes, deadbeat seconds, date

Cal. 770 is what produces that jump. An extra wheel holds the seconds hand and lets it go once per second, so the hand lands on a marker and stops there instead of crossing it. The same calibre carries the Gyrolab balance, a non-circular balance wheel shaped to cut air drag, and that pairing is what separates the 8018120 from every other three-hand JLC. The result ticks like quartz and runs on a mechanical train.

What Collectors Notice

The deadbeat seconds complication immediately identifies the Geophysic to anyone who knows watches. Most mechanical automatics sweep at six or eight beats per second, so a jumping seconds hand signals something unusual under the dial. Jaeger-LeCoultre built the original Geophysic as a scientific instrument, and the True Second carries that precision-oriented DNA forward. Compare this against the Master Geographic Q1422421 to see how two technically ambitious watches within the same brand diverge in purpose: one tracks seconds with unusual accuracy, the other tracks entire time zones. Both are shelved in the same Master Control category here, though Geophysic is its own line at Jaeger-LeCoultre.

This vs Other Versions

The Geophysic True Second stands apart from every other Master Control reference because of that single complication. Where the Ultra Thin models compete on thinness and the Geographic models compete on travel functionality, the 8018120 competes on mechanical novelty. The jumping seconds hand draws attention in a way that a smooth sweep never does. The JLC Geophysic True Second 8018120 clone suits the wearer who values a talking-point complication wrapped inside a case that still reads as a refined dress watch.

Geophysic is a separate JLC line, so the pieces nearest to it here are the 899 Dates and 939A Geographics gathered on the Master Control page this reference is shelved under. Whether a jumping seconds hand is worth paying for at all comes down to what separates a good JLC clone from a cheap one.

Specifications

• Model: JLC Geophysic True Second 8018120 clone
• Reference: 8018120 (Q8018120)
• Case: polished stainless steel, 11.7 mm thick
• Case size: 39.6 mm
• Dial: silvered, faceted baton markers at every hour, no numerals, date disc matched to the dial colour
• Complications: deadbeat (jumping) seconds, date at 3 o’clock
• Movement: clone Cal. 770, automatic, 28,800 vph
• Power reserve: 37 hours (genuine Cal. 770: 40 hours)
• Water resistance: 50 m (same as genuine)
• Crystal: sapphire
• Bracelet: polished and brushed stainless steel