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The Encyclopedia of Horology

Wristwatch · GMT wristwatch

Bulgari Diagono Professional GMT 40 S

Partially verified

This Bulgari Diagono Professional GMT, reference GMT 40 S, is an automatic self-winding wristwatch featuring a tonneau-shaped stainless steel case measuring 40 mm in diameter. The watch includes a 24-hour graduated bidirectional revolving bezel for AM-PM indication. The silver sunburst-finished dial displays center seconds, a subsidiary date dial located at 6 o'clock, and a diurnal/nocturnal 24-hour scale. The timepiece is fitted with an integrated black rubber strap secured by a stainless steel Bulgari deployant clasp. It features a water-resistant construction with a screwed case-back and a crown protected by guards. Two round screwed push-pieces at 2 and 4 o'clock allow for independent adjustment of the two-time zone function, while a third push-piece at 8 o'clock controls the date. The movement is officially certified as a chronometer. The watch is signed on the dial, case, and movement.

Front view of the Bulgari Diagono Professional GMT 40 S, highlighting the silver sunburst dial, 24-hour bezel, and push-piece layout.
Front view of the Bulgari Diagono Professional GMT 40 S, highlighting the silver sunburst dial, 24-hour bezel, and push-piece layout. — Antiquorum. Rights pending — permission not yet requested. Original source

Catalogue identity

Source
catalog.antiquorum.swiss
Category
Wristwatch · GMT wristwatch
Maker / attribution
Bulgari
Reference
GMT 40 S
Catalogue / lot identifier
70
Source-reported date
circa 2010
Source-reported place
Switzerland
Source-reported serial
L 08590

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

The Bulgari GMT 40 S features a stainless steel, tonneau-shaped case measuring 40 mm. The design includes crown guards that protect the winding crown, and the watch is engineered to be water-resistant with a screwed case-back. The bezel is a bidirectional revolving component graduated with a 24-hour scale for AM-PM reference.

The dial is finished in a silver sunburst pattern. It incorporates center seconds and three specific complications: a subsidiary date dial at the 6 o'clock position, a central 24-hour AM-PM scale for day and night indication, and a two-time zone display. Adjustment for the time zone is managed via round screwed push-pieces positioned at the 2 and 4 o'clock marks, while the date is adjusted by a similar push-piece at 8 o'clock.

Evidence for this section
  • “Stainless steel, self-winding, tonneau-shaped, aviator’s wristwatch, water-resistant with screwed case-back, winding crown protected by the crown guards”
  • “24-hour graduated bidirectional revolving bezel for the AM-PM indication”
  • “silver “sunburst” colour dial with centre-seconds and three horological complications”

Movement and Functionality

The watch operates on a self-winding mechanical movement that is officially certified as a chronometer. The functions provided include a local time display, a second time zone, a 24-hour diurnal and nocturnal indicator, and a date display. The watch is signed across the dial, case, and movement to confirm its origins.

Adjustments for the complications are facilitated through a set of integrated push-pieces. The independent adjustment of the second time zone is achieved via the push-pieces at 2 and 4 o'clock, while the date function is regulated through the push-piece located at the 8 o'clock position.

Evidence for this section
  • “self-winding, date, AM-PM indication, two-time zone”
  • ““Chronometer Officially Certified””
  • “Two-time zone (same central hour index independently adjustable by the round screwed push-pieces at 2 and 4 o’clock”

Identification and Provenance

This watch is identified as part of the Diagono Professional line. According to the provided documentation, the object is dated to circa 2010. The case number is recorded as L 08590. The timepiece is currently fitted with an integrated black rubber strap and a stainless steel Bulgari deployant clasp.

The auction description reports the condition of the watch, assigning a general grade of AA. Specifically, the case and dial are rated as '1', indicating they are in as-new condition, while the movement is also assigned a grade of '1'.

Evidence for this section
  • “Model “Diagono Professional””
  • “Year circa 2010”
  • “Case No. L 08590”
  • “Grading System Grade: AA”

Open research questions

  • What is the specific movement caliber used within the GMT 40 S?
  • What are the specific horological specifications of the 'Chronometer Officially Certified' certification for this model?

Source evidence

Recorded claims and source quotations for Bulgari Diagono Professional GMT 40 S
FieldSource-reported valueSource quotation
MakerBulgari“Bulgari, Rome and Neuchâtel”
ReferenceGMT 40 S“Ref. GMT 40 S”
SerialL 08590“Case No. L 08590”
Case MaterialStainless steel“stainless steel”
FunctionsDate, AM-PM, Two-time zone“date, AM-PM indication, two-time zone”
Diameter40 mm“Diameter 40 mm.”
Bezel24-hour bidirectional“24-hour graduated bidirectional revolving bezel”
StrapRubber with deployant clasp“integrated black rubber Bulgari strap, stainless steel Bulgari deployant clasp”

Visible details

  • Bidirectional 24-hour revolving bezel
  • Screwed push-pieces at 2, 4, and 8 o'clock
  • Integrated rubber strap with deployant clasp
  • Silver-tone sunburst dial finish

Research qualifications

  • The exact technical composition of the automatic movement is not detailed in the source.
  • The source provides a grade of '1' for the movement without further descriptive detail.

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

Consulted source

Bulgari - Ref. GMT 40 S, self-winding, date, AM-PM indication, two-time zone; “Diagono Professional”; stainless steel

Reviewed 2026-10-26 · Record 0e973ebfa1

Terms in this record

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

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