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The Encyclopedia of Horology

Serial-number guide

Jaeger-LeCoultre Serial Numbers

Partially verified

What a Jaeger-LeCoultre serial number can establish, what it cannot, and how to record a date estimate another researcher could check.

Jaeger-LeCoultre movement markings

Jaeger-LeCoultre. Gold-plated metal pocket watch – Late 20th Century
Jaeger-LeCoultre. Gold-plated metal pocket watch – Late 20th Century — WatchMuseum.org, © WatchMuseum.org, used with permission. WatchMuseum.org catalogue record
Jaeger-LeCoultre. Gold-plated metal pocket watch – Late 20th Century
Jaeger-LeCoultre. Gold-plated metal pocket watch – Late 20th Century — WatchMuseum.org, © WatchMuseum.org, used with permission. WatchMuseum.org catalogue record
Jaeger-LeCoultre. Gold-plated metal pocket watch – Late 20th Century
Jaeger-LeCoultre. Gold-plated metal pocket watch – Late 20th Century — WatchMuseum.org, © WatchMuseum.org, used with permission. WatchMuseum.org catalogue record

Movement markings — maker name, grade, serial number and jewelling — are the evidence base for any serial-number attribution.

Method

Reading the number, step by step

  1. 1. Find the movement number

    Case and movement numbering are independent series at JLC as elsewhere; additionally, because JLC was a major ébauche and complete-movement supplier to other manufacturers for much of the twentieth century, a case signed by a different brand housing a JLC-made movement is a normal, documented trade practice rather than evidence of tampering, but it does mean two separate research questions (case-signature brand, and movement maker) may need two separate archives.

  2. 2. Understand what it encodes

    The movement (calibre) number is the primary reference for a Jaeger-LeCoultre-signed piece; for movements supplied to third parties, the correct archive to consult may be the retailing brand's own records rather than JLC's, and this must be established first from the calibre's markings and construction.

  3. 3. Judge how precise the date can be

    Partially verified for JLC's own branded lines via the manufacturer's heritage service; needs-research on a case-by-case basis for movements known or suspected to have been supplied to other houses, since attribution requires calibre identification before any dating claim can be made.

  4. 4. Check the records behind the tables

    Jaeger-LeCoultre maintains a heritage archive at its Vallée de Joux manufacture and offers an extract-style heritage service for movements bearing a JLC-attributable number; because JLC also supplied ébauches and complete movements to numerous other houses (including, historically, various models retailed or cased under other names), the presence of a JLC-style calibre does not by itself establish which brand's archive, if any, is the correct one to consult.

Quick facts

Manufacturer
Jaeger-LeCoultre
Dating confidence
Estimate only — see notes
Editorial status
Partially verified

Sources & references

  1. Jaeger-LeCoultre, published information on heritage/archive extract services
  2. Community-maintained calibre-identification references documenting JLC's historical role as a movement supplier to other houses

Where sources disagree, the disagreement is stated rather than resolved silently.

Limits

What the number does not prove

Questions

Frequently asked

Where is the serial number on a Jaeger-LeCoultre watch?
Case and movement numbering are independent series at JLC as elsewhere; additionally, because JLC was a major ébauche and complete-movement supplier to other manufacturers for much of the twentieth century, a case signed by a different brand housing a JLC-made movement is a normal, documented trade practice rather than evidence of tampering, but it does mean two separate research questions (case-signature brand, and movement maker) may need two separate archives.
What do Jaeger-LeCoultre serial numbers mean?
The movement (calibre) number is the primary reference for a Jaeger-LeCoultre-signed piece; for movements supplied to third parties, the correct archive to consult may be the retailing brand's own records rather than JLC's, and this must be established first from the calibre's markings and construction.
How accurate is dating a Jaeger-LeCoultre watch by serial number?
Partially verified for JLC's own branded lines via the manufacturer's heritage service; needs-research on a case-by-case basis for movements known or suspected to have been supplied to other houses, since attribution requires calibre identification before any dating claim can be made.
Where are Jaeger-LeCoultre production records held?
Jaeger-LeCoultre maintains a heritage archive at its Vallée de Joux manufacture and offers an extract-style heritage service for movements bearing a JLC-attributable number; because JLC also supplied ébauches and complete movements to numerous other houses (including, historically, various models retailed or cased under other names), the presence of a JLC-style calibre does not by itself establish which brand's archive, if any, is the correct one to consult.

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