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The Encyclopedia of Horology

Wristwatch · Chronograph

Rolex Cosmograph Daytona 16520

Partially verified

This Rolex Cosmograph Daytona reference 16520 is a stainless steel automatic chronograph dating to 1996. The watch features a black dial with three subsidiary registers, identified as a 'Mk5' tritium configuration with an upright numeral '6' in the hour totalizer. The dial is marked with 'T SWISS MADE T' at the six o'clock position. The case measures 40mm in diameter and is paired with a steel Oyster bracelet, reference 78390, featuring polished center links, '503B' end links, and a clasp marked with code 'Z6'. The movement is the Rolex calibre 4030, an automatic chronograph mechanism described by the vendor as a modified version of the Zenith El Primero. The auction description reports that the watch has undergone service by their internal watchmaker and retains its original components, including a black dial showing subtle signs of ageing in the sub-dials.

The Rolex Cosmograph Daytona 16520 showing the black dial, three subsidiary registers and Oyster bracelet
The Rolex Cosmograph Daytona 16520 showing the black dial, three subsidiary registers and Oyster bracelet — Bulang & Sons. Rights pending — permission not yet requested. Original source

Catalogue identity

Source
www.bulangandsons.com
Category
Wristwatch · Chronograph
Maker / attribution
Rolex
Reference
16520
Catalogue / lot identifier
Source URL identifies the listing
Source-reported date
1996
Source-reported place
Not established
Source-reported serial
T89xxxx

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 Bracelet

The watch is housed in a 40mm steel case with a tachymeter bezel. The design incorporates the characteristic screw-down chronograph pushers and winding crown associated with the Oyster case architecture. The case displays a combination of polished and brushed surfaces, consistent with the 16520 reference specifications.

The watch is mounted on a stainless steel Oyster bracelet identified as reference 78390. This bracelet includes polished center links and is secured by end links stamped 503B. The clasp is recorded with the code Z6, which is consistent with the late 1990s period of manufacture for this specific watch.

Evidence for this section
  • “40mm steel case”
  • “Oyster bracelet, ref. 78390, featuring polished centre links, clasp code ‘Z6’ and 503B end links.”

Dial and Hands

The black dial is characterized by three subsidiary registers for the chronograph functions. According to the provided details, this is an original tritium-luminous dial in the 'Mk5' configuration. A distinguishing feature of this specific layout is the upright numeral '6' located within the lower hour register.

The luminous material on the dial and hands shows subtle ageing, resulting in a creamy tone in the sub-dials. The dial is signed at the base with the text 'T SWISS MADE T', confirming the use of tritium as the original luminous compound, and retains its original finish.

Evidence for this section
  • “The tritium dial retains its mk5 layout , including the upright ‘6’ in the lower hours register.”
  • “The black dial remains crisp and deep, while the three sub-dials have taken on a very subtle creamy tone over the years.”

Movement and Service

The watch is powered by the Rolex calibre 4030, an automatic movement that functions as the base for the chronograph complication. The source notes that this movement was derived from the Zenith El Primero design, which was subsequently modified by Rolex for use in the 16520 reference during this production era.

The auction description reports that the movement has been fully serviced by the vendor's internal watchmaker.

Evidence for this section
  • “Inside, the Rolex calibre 4030 — based on the Zenith El Primero — has been fully serviced by our watchmaker.”
  • “Calibre 4030 movement (modified Zenith El-Primero) automatic”

Open research questions

  • Does the Z6 clasp code definitively align with the T89xxxx serial number range in Rolex production records?
  • Are there any visible service marks on the inner case back that corroborate the recent service history reported by the vendor?

Source evidence

Recorded claims and source quotations for Rolex Cosmograph Daytona 16520
FieldSource-reported valueSource quotation
MakerRolex“Rolex Cosmograph Daytona Reference 16520”
Reference16520“Rolex Cosmograph Daytona Reference 16520”
SerialT89xxxx“T89xxxx dating to 1996”
Calibre4030“Calibre 4030 movement (modified Zenith El-Primero) automatic”
Bracelet Reference78390“Oyster bracelet reference 78390”
Clasp CodeZ6“clasp code ‘Z6’”
Dial TypeMk5 tritium“The tritium dial retains its mk5 layout”

Visible details

  • Dial marked 'T SWISS MADE T' at the six o'clock position
  • Upright '6' numeral in the bottom sub-dial
  • Brushed and polished steel Oyster bracelet links
  • Screw-down chronograph pushers and winding crown

Research qualifications

  • The exact month of production is not specified within the year 1996
  • The description of sub-dial colouration as 'creamy' is subjective

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

Consulted source

Rolex Cosmograph Daytona 16520 Black Dial T-series

Reviewed 2026-11-02 · Record 80848f82e5

Terms in this record

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

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