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The Encyclopedia of Horology

Wristwatch · Square-button chronograph

Breguet 18K Yellow Gold Chronograph No. B340

Partially verified

This Breguet wristwatch, identified as No. B340, is an 18K yellow gold chronograph produced circa 1940. The piece features a three-body case design with a polished finish, characterized by a curved bezel and concave lugs. The brushed silver dial is adorned with applied yellow gold Arabic numerals and dot indexes. It tracks time using central hours and minutes with yellow gold baton hands, while incorporating an outer minute and fifths-of-a-second track, an outermost tachometer scale, and two subsidiary dials for constant seconds and a 30-minute register. The movement is the rhodium-plated 13-ligne Caliber 340, which employs a straight-line lever escapement, a monometallic balance, and a self-compensating blued steel balance spring. The overall diameter of the watch is 35 mm, with a case thickness of 12 mm. The auction description notes the presence of original hands and specifies the dial is signed.

Front view of the Breguet 18K yellow gold chronograph wristwatch with brown leather strap.
Front view of the Breguet 18K yellow gold chronograph wristwatch with brown leather strap. — Antiquorum. Rights pending — permission not yet requested. Original source

Catalogue identity

Source
catalog.antiquorum.swiss
Category
Wristwatch · Square-button chronograph
Maker / attribution
Breguet
Reference
Not recorded
Catalogue / lot identifier
102
Source-reported date
circa 1940
Source-reported place
Not established
Source-reported serial
B340

Source-reported attribution and specifications are not independent authentication. A listing does not establish present ownership, current display, availability or permission to reproduce.

Object description

Case and Dial Design

The watch is housed in an 18K yellow gold three-body case. The exterior features a polished finish, complemented by a curved bezel and concave lugs, which provide the profile for the 35 mm diameter housing. The case measures 12 mm in thickness.

The dial is finished in a brushed silver tone, accented by applied yellow gold Arabic numerals and dot indices. For timing functions, the dial includes outer minute and fifths-of-a-second markings, alongside an outermost tachometer graduation. Two subsidiary dials are integrated at the register positions for the seconds and the 30-minute chronograph counter, accompanied by yellow gold baton hands. The auction description reports the dial is signed.

Evidence for this section
  • “Three-body, polished, curved bezel, concave lugs”
  • “Brushed silver with applied yellow gold Arabic numerals and dot indexes”
  • “outermost tachometer graduation, subsidiary dials for the seconds and 30- minute register”
  • “Dial signed”

Movement Specifications

The watch is powered by the Caliber 340, a movement measuring 13 lignes in diameter. It is constructed with rhodium plating and utilizes a straight-line lever escapement.

The timing regulation is managed by a monometallic balance paired with a self-compensating blued steel balance spring. An index regulator is included within the movement structure.

Evidence for this section
  • “Cal. 340, 13''', rhodium-plated, straight-line lever escapement”
  • “monometallic balance, self-compensating blued steel balance spring, index regulator”
  • “Overhaul recommended, at buyer's expense”

Condition and Attribution

The object is attributed to a production date of circa 1940. The hands are recorded as original to the piece. The case is numbered B340.

The auction description provides grading for the individual components of the watch. The overall grade is listed as AA, with the case condition noted as good with scratches, and the dial noted as good with slight oxidation. The movement is similarly rated as good, subject to the recommendation for servicing.

Evidence for this section
  • “Made circa 1940”
  • “Grading System Grade: AA Very good”
  • “Case: 3-9 Good Scratched”
  • “Dial: 3-6-01 Good Slightly oxidized”

Open research questions

  • What is the specific historical production volume for Caliber 340 chronographs during this period?
  • Does the number B340 correlate to specific archival records held by the manufacturer regarding the original retail destination of this chronograph?

Source evidence

Recorded claims and source quotations for Breguet 18K Yellow Gold Chronograph No. B340
FieldSource-reported valueSource quotation
MakerBreguet“Breguet”
Serial NumberB340“No. B340”
Case Material18K yellow gold“18K yellow gold wristwatch”
MovementCaliber 340“Cal. 340”
Diameter35 mm“Diam. 35 mm”
Thickness12 mm“Thickness 12 mm”
Dial DescriptionBrushed silver“Brushed silver”
HandsOriginal“HANDS Original”

Visible details

  • Case features concave lugs and a polished finish
  • Dial displays applied gold Arabic numerals and dot markers
  • Two subsidiary dials for chronograph register and constant seconds

Research qualifications

  • Movement condition is noted as needing overhaul
  • Dial is described as slightly oxidized

Photograph identity and source facts were screened before import; rights clearance remains pending.

Consulted source

Yellow Gold Chronograph Breguet, No. B340. Made circa 1940. Fine and rare, 18K yellow gold wristwatch with square-button chronograph, register and tachometer.

Reviewed 2026-10-26 · Record 85db292cb1

Terms in this record

Glossary explanations for terms named in this object’s record.