Short answer
A fake Jaeger-LeCoultre 1558420 is a counterfeit of the Jaeger-LeCoultre Master Control Calendar. The real ref. 1558420 has a 40 mm steel case, a triple calendar, and a moonphase. Copies fail on case thickness, dial print, moonphase disc, movement finish, and paperwork.
What the real ref. 1558420 is
Jaeger-LeCoultre identifies ref. 1558420 as a Master Control Calendar. The watch has a stainless steel case, a silver dial, day and month windows, a date hand, and a moonphase at 6 o'clock. The movement is automatic. The caseback has a sapphire crystal.
High-risk tells
- Case thickness. Measure the case. A copy can sit thicker or thinner than the real watch. Compare against official specs.
- Dial print. Check the logo, the text, and the minute track. Copy print can sit low, high, or uneven.
- Moonphase disc. The real disc has a deep blue field and clean stars. A fake disc can look flat or printed off-center.
- Calendar windows. Check day and month alignment. The date hand should point to the correct date.
- Movement. The real watch uses JLC calibre 866. A counterfeit may use a generic automatic movement with a calendar module.
- Caseback. Check engravings, reference numbers, and finish. Copy engravings can lack depth.
Papers and seller checks
Compare the serial number on the caseback with the paperwork. A copied warranty card can have wrong fonts or no dealer stamp. Ask for a service record. Meet at a watchmaker for a movement check. A low price is a risk sign. The 1558420 is a steel calendar watch, not a cheap entry model.
Buying rule
Do not rely on photos alone. A hands-on check by a watchmaker who knows Jaeger-LeCoultre movements is the safest step. If the seller blocks that check, walk away.