The most dependable check on a watch sold as Jaeger-LeCoultre reference 1568420 is an Extract from the Archives from the brand combined with a movement inspection by an accredited watchmaker. Everything else is a filter. The criteria that decide the outcome are the caseback code and its engraving, the finish and behaviour of the movement, the dial printing and hand work, the physical dimensions against published specs, the paperwork trail, and the asking price against the real secondary market. Work through them in that order, and a counterfeit usually fails before you reach the last one.

What the number 1568420 refers to

Jaeger-LeCoultre marks modern watches with a reference code that begins with the letter Q, so the string 1568420 in a listing is normally the numeric part of a code such as Q1568420. A separate serial number is engraved near it. The two do different jobs. The reference says which model the watch is. The serial identifies that one watch. Sellers who quote only the numbers, and never a photo of the full caseback, are usually hiding something.

• Pros: the code is free to read and shows up in almost every listing photo.
• Cons: laser engraving copies a code in seconds, so a correct number proves nothing on its own.

Best for: a first pass. If the reference is missing, the serial repeats across other listings, or the seller refuses a clear caseback shot, end the conversation there.

Caseback engraving and finish

Genuine casebacks carry sharp, evenly cut characters with clean inner corners and consistent depth. The surrounding brushed or polished surfaces run in straight, unbroken lines. Counterfeit casebacks often show shallow cuts, rounded letter edges, polishing that bleeds into the engraving, and screws with heads that sit proud of the surface or show damaged slots from repeated opening.

• Pros: visible in a phone photo, and hard to fake at the level of a real stamping tool.
• Cons: some genuine service casebacks are replaced, so a mismatch is not always proof of a fake.

Best for: remote buying, where you only have images to work with.

Movement finish and winding feel

Open the caseback, or ask for a movement photo before you pay. Look for Geneva stripes with sharp, parallel edges, perlage that overlaps without gaps, blued or polished screw heads, and a rotor engraved with the brand name and the caliber number rather than printed on. Then handle the watch. A genuine movement winds with light, even resistance and the rotor turns without scraping. Cheap copies feel gritty, spin loosely, and often run a generic or cloned caliber that does not match the reference.

• Pros: the single hardest detail to reproduce at a low price.
• Cons: requires a caseback tool, a loupe, and some experience.

Best for: in-person deals and any high-value purchase.

Dial printing, hands, and applied markers

Under a loupe, genuine printing has solid, unbroken strokes and a logo with clean serifs. Subdials line up with the case center, and any moonphase or calendar disc sits flat and well finished. Fakes show fuzzy edges, uneven spacing between markers, hands with flat or scratched bevels, and date windows that cut into the dial print. Check the Swiss Made marking at the bottom of the dial and whether it follows the rules for the marking.

• Pros: magnification reveals faults that normal photos hide.
• Cons: dials are the most copied part, so a perfect dial alone means little.

Best for: confirming a suspicion raised by the caseback or movement.

Dimensions, weight, and proportions

Measure the case diameter, thickness, and lug width with calipers, then compare against the published specification for the reference. Weigh the watch head on a kitchen scale. Fakes are frequently a fraction of a millimeter too thick, wear heavier or lighter than the real piece, and use spring bars or crowns that sit at the wrong height. A crown that does not match the case finish, or a crystal with visible distortion at the edges, is another warning.

• Pros: numbers do not argue, and the tools cost little.
• Cons: service replacement parts can shift measurements on a genuine watch.

Best for: narrowing down a shortlist of two or three watches before paying for an inspection.

Papers, service records, and the archive check

The Extract from the Archives is a document the brand issues on request that confirms the reference and the production date of a specific serial. It is not free and not every watch has one, but a seller who claims one must produce a document that matches the serial on the caseback. Service invoices from an authorized center, with the serial printed on them, carry real weight. Boxes and warranty cards do not, because they are copied and sold loose in large numbers.

• Pros: the only check that ties the reference and the serial together at the source.
• Cons: takes time to request, and vintage or altered watches may not qualify.

Best for: closing a deal, or settling a dispute after purchase.

Price sanity and which check to use when

Compare the asking price with live listings for the same reference on the secondary market. A large gap is the oldest signal there is. For a stranger online, request the caseback and movement photos, then pay for an archive check and a watchmaker inspection. For a face-to-face sale, ask to see the movement and time it over a few hours. If you already own the watch and doubt it, take it to an authorized service center. A counterfeit carries no warranty, no parts support, and no resale value, so the cost of a proper check is always smaller than the cost of guessing.