Short answer
Most watches sold as a "Jaeger-LeCoultre Reverso 398" are replicas built around a reference string that does not come from a Jaeger-LeCoultre catalog. The "398" is a listing tag, not a factory reference. Genuine Reverso models carry a Q-prefix reference (Q2548520, Q3848420 and similar) plus a separate caseback stamp, so a seller who treats "398" as proof of authenticity has already shown you the problem. Check the flip mechanism, case dimensions, engraving depth and movement before money changes hands.
What the "398" number means in listings
Replica listings reuse numbers for two reasons. Some sellers copy a code from a caseback they photographed once, and others invent a plausible looking tag so a generic product appears cataloged. A real Reverso has two identifiers: the model reference, printed in the catalog and on paperwork, and a case number stamped on the back. When a listing offers only "398" and no reference, no case number, and no matching documentation, treat the watch as unverified at best.
Prerequisites
- A 10x loupe or a macro lens for phone photos
- Digital calipers that read to 0.1 mm
- Reference photos of a known genuine Reverso in the same case size
- Full-resolution seller photos plus a short video of the case flipping
- Bright, indirect light and a steady surface
Inspection procedure
- Ask the seller for the reference number and the caseback number in writing, then compare both against the model being claimed.
- Measure the case width with calipers and match it to the published dimensions for that Reverso size.
- Measure case length, then compare it to the same reference, since replicas often run 0.5 to 1 mm long.
- Measure thickness at the center of the case and note any figure more than 0.3 mm off spec.
- Flip the case through its full travel and feel for grit, wobble or a carriage that stops short of the rails.
- Check the gap between the carriage and the case frame on both sides with the loupe.
- Study the dial printing at 10x for fuzzy edges, uneven stroke weight or lettering that sits off center.
- Compare the guilloche or sunray finish against your reference photos, watching for shallow or irregular grooves.
- Look at the hands in raking light, since genuine blued hands shift color while painted replicas stay flat.
- Wind the crown and set the hands, noting any grinding, looseness or backlash in the stem.
- Request a clear movement photo and a timegrapher reading before agreeing to a price.
- Inspect the caseback engraving depth and crispness, because laser etching on replicas looks shallow and rounded.
Reverso-specific tells
The Reverso is harder to copy than a round dress watch because the case slides on rails and flips on two pins. On a genuine watch the carriage moves with light, even resistance and locks into the wearing position with an audible click. Fakes tend to bind halfway, sit proud of the frame, or show a visible seam where the carriage meets the case. Look at the corners of the case too. A real Reverso has crisp, polished bevels and a consistent brushed grain on the sides, while replica cases often round off the corners during polishing.
Movement and caseback
Ask for a photo of the movement with the caseback removed. Genuine Jaeger-LeCoultre calibers show Geneva stripes, blued screws, jeweled bearings and engraved markings that sit under the finish rather than on top of it. Replicas commonly use a decorated generic movement with printed or stamped text, and rotor engraving that looks painted. Caseback stamps also matter: on authentic watches the reference and case numbers are cut into the metal with sharp walls, not etched into a smooth surface.
Seller red flags
- A price far below the market for the same reference in similar condition
- Photos that avoid the caseback, the movement or the flip mechanism
- Pressure to pay through a method with no buyer protection
- Claims that the watch is "the 398 model" without any Q-prefix reference
- Refusal to send a video of the case sliding and flipping
Bottom line
If the reference does not resolve to a real Jaeger-LeCoultre catalog entry, the measurements miss spec, the carriage binds and the movement photo shows a decorated generic caliber, you are looking at a replica. Walk away, or price it as what it is. When a seller cannot produce clear photos of the caseback numbers and the movement, no other detail in the listing can rescue the deal.