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The Encyclopedia of Horology

Wristwatch · Military-style wristwatch

Longines 'Sei Tacche' Wristwatch with 24-Hour Dial

Partially verified

This is a vintage Longines military-style wristwatch dating to circa 1945, fitted in a 'Sei Tacche' screw-back case. The watch displays a light-toned speckled dial bearing Arabic numerals, an inner red-toned 13–24 hour track, central seconds, and blued steel hands with aged luminous infill. The manual-wind movement is stated to be a Longines calibre 23M with 17 jewels. According to the seller, the watch features matching numbers on the case and lugs, and is accompanied by an Extract from the Archives from Longines.

Front view of the Longines dial showing central hands, Arabic numerals, and 24-hour markings
Front view of the Longines dial showing central hands, Arabic numerals, and 24-hour markings — Vintage Watch Specialist. Rights pending — permission not yet requested. Original source

Catalogue identity

Source
vintagewatchspecialist.com
Category
Wristwatch · Military-style wristwatch
Maker / attribution
Longines
Reference
Not recorded
Catalogue / lot identifier
vws2696
Source-reported date
c. 1945
Country
Switzerland

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

Visual Dial and Display Features

Direct visual inspection reveals a cream or light-coloured dial displaying aged speckling across its face. The dial layout includes an outer chapter ring marked with minute tick divisions and Arabic numerals at five-minute intervals, a primary hour scale in Arabic numerals, and an inner concentric track featuring 13–24 hour markings.

The time is indicated by blued steel hands with discoloured luminous infill alongside a slim central seconds hand. A fluted winding crown is positioned on the case flank at 3 o'clock. In the source text, the vendor describes this arrangement as a "military-style 24-hour dial" and notes "blued steel hands with original lume."

Evidence for this section
  • “Cream or light-coloured dial with aged speckling/patina”
  • “Blued steel hands with discoloured luminous infill”
  • “Inner printed 13–24 hour numeral track”
  • “Outer chapter ring with five-minute Arabic increments and minute tick marks”
  • “Fluted winding crown at the 3 o'clock position”
  • “The military-style 24-hour dial is in superb vintage condition with a nice even speckling of attractive patina and blued steel hands with original lume.”

Case Construction and Stated Dimensions

The listing describes the watch as featuring a "Sei Tacche screw-back case," noting that "these case backs were milled with three or six notches designed to aid in tightening the threaded case backs to the case to provide adequate protection from moisture and dust". The listing also claims that the watch has "matching case and lug numbers."

Reported dimensions show a discrepancy in width within the source: the overview prose states the watch is "relatively small by today's standards at 32mm", while the technical specification table lists "Width 33mm". The table further records a lug height of "41mm", a lug width of "18mm", and specifies a "Plexiglass" crystal.

Evidence for this section
  • “Sei Tacche screw-back case - t hese case backs were milled with three or six notches designed to aid in tightening the threaded case backs to the case to provide adequate protection from moisture and dust”
  • “matching case and lug numbers”
  • “The watch is relatively small by today's standards at 32mm however, it wears well on the wrist and its meaty case gives the feel of a more substantial size.”
  • “Width 33mm”
  • “Lug Height 41mm”
  • “Lug width 18mm”
  • “Crystal Plexiglass”

Reported Movement and Archival Documentation

The internal mechanism is not visible in the provided image. According to the seller's specifications, the movement is a mechanical manual-wind Longines "Calibre 23M" with "17" jewels and a reported power reserve of "41 Hours".

The watch is listed with a "Date of Issue 1945" (or circa 1945). The seller states that they "applied for an Extract of the Archive from Longines which provides documentation of our findings about this watch and will be supplied with the watch upon purchase."

Evidence for this section
  • “Movement Type Mechanical”
  • “Winding Manual”
  • “Calibre 23M”
  • “Jewels 17”
  • “Power Reserve 41 Hours”
  • “Date of Issue 1945”
  • “We applied for an Extract of the Archive from Longines which provides documentation of our findings about this watch and will be supplied with the watch upon purchase.”

Source Discrepancies and Limitations

There is an unresolved contradiction in the source text regarding the case material. The initial overview bullet points list "Case Chrome Topped", whereas the technical specification table denotes "Case Stainless Steel".

Because neither the movement, inner case back, lug stamping, nor the referenced Longines Extract of the Archive are visible in the provided imagery, claims regarding the calibre number, matching lug stamps, and precise dating rely entirely on the seller's listing.

Evidence for this section
  • “Case Chrome Topped”
  • “Case Stainless Steel”

Open research questions

  • What metal composition is the case (resolving the contradiction between 'Chrome Topped' and 'Stainless Steel')?
  • What specific archival information and movement/case serial numbers are stated on the Longines Extract of the Archive?
  • What are the specific numerical stamps on the case back and lugs that are stated to match?

Source evidence

Recorded claims and source quotations for Longines 'Sei Tacche' Wristwatch with 24-Hour Dial
FieldSource-reported valueSource quotation
Calibre23M“Calibre 23M”
Jewel Count17“Jewels 17”
Case DesignSei Tacche screw-back case“Sei Tacche screw-back case”
Lug Width18mm“Lug width 18mm”
Movement TypeMechanical manual-wind“Movement Type Mechanical”
Case Width (Prose Description)32mm“The watch is relatively small by today's standards at 32mm”
Case Width (Specification Table)33mm“Width 33mm”
Lug Height41mm“Lug Height 41mm”
Stated Power Reserve41 Hours“Power Reserve 41 Hours”
Date of Issue (Source Table)1945“Date of Issue 1945”

Visible details

  • Cream or light-coloured dial with aged speckling/patina
  • Blued steel hands with discoloured luminous infill
  • Inner printed 13–24 hour numeral track
  • Fluted winding crown at the 3 o'clock position
  • Outer chapter ring with five-minute Arabic increments and minute tick marks

Research qualifications

  • Contradiction in case material description: stated as 'Chrome Topped' in initial listing overview but specified as 'Stainless Steel' in the technical table.
  • Movement and interior case back are not visible in the provided image; calibre 23M and matching numbers rely entirely on seller statements.

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

Consulted source

Longines Sei Tacche with a Rare 24 Hour Dial - c.1945 - Matching Case – Vintage Watch Specialist

Reviewed 2026-10-21 · Record 94c82ce274

Terms in this record

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

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