Skip to content
The Encyclopedia of Horology

Wristwatch · Diver's wristwatch

Seiko 'Grandfather Tuna' Professional 600 Diver

Partially verified

This is a vintage Seiko Professional 600 diver's wristwatch, reference 6159-7010, dated by the seller to circa 1975. Commonly designated as the 'Grandfather Tuna', this early dial variant is distinguished by the text 'PROFESSIONAL 600' without an accompanying 'm' meter designation. The watch features a dark protective outer shroud secured by screws around the titanium case, an offset crown near 4 o'clock, and a rotating black dive bezel. The black dial displays luminescent round and triangular hour markers with a framed date aperture at 3 o'clock. The seller reports an automatic mechanical calibre 6159a movement and an original Seiko vented rubber strap.

Dial and shrouded titanium case of the Seiko 6159-7010 'Grandfather Tuna' diver
Dial and shrouded titanium case of the Seiko 6159-7010 'Grandfather Tuna' diver — Vintage Watch Specialist. Rights pending — permission not yet requested. Original source

Catalogue identity

Source
vintagewatchspecialist.com
Category
Wristwatch · Diver's wristwatch
Maker / attribution
Seiko
Reference
6159-7010
Catalogue / lot identifier
vws2313
Source-reported date
c. 1975
Country
Japan

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 Construction and Dimensions

The watch features a distinctive shrouded case design, with the seller listing the core case material as titanium and reporting a case width of 50.5mm excluding the crown, alongside a 50mm lug-to-lug height and a 22mm lug width. In direct observation, a dark protective outer shroud encircles the case perimeter and is secured by exposed screws, leaving cutouts that expose the edges of the rotating bezel.

The case incorporates an offset grooved crown positioned near 4 o'clock. The crystal covering the dial is listed in the seller specification table as mineral glass, bordered by a black rotating bezel carrying calibrated elapsed-time markings and a luminous triangular marker at 12 o'clock.

Evidence for this section
  • “Width (without crown) 50.5mm”
  • “Lug height (lug to lug) 50mm”
  • “Protective dark shroud encircles the case perimeter, fastened by exposed screws”
  • “Offset grooved crown positioned near 4 o'clock”

Dial Configuration and Early Variant Markings

The watch is fitted with a black dial bearing circular luminescent indices, a broad triangular marker at 12 o'clock, a lollipop seconds hand, and a framed date aperture situated at 3 o'clock.

Below 12 o'clock, the dial is signed 'SEIKO / AUTOMATIC', while the text above 6 o'clock reads 'PROFESSIONAL / 600'. The seller notes that this specific example lacks the 'm' for meters next to the depth rating, presenting it as an early production iteration.

Evidence for this section
  • “Dial text reads 'SEIKO / AUTOMATIC' below 12 o'clock and 'PROFESSIONAL / 600' above 6 o'clock without an 'm'”
  • “lacks the “m” for “meters” next to the depth rating”
  • “Black dial with circular luminescent indices, triangular 12 o'clock marker, lollipop seconds hand, and date aperture at 3 o'clock”

Reported Movement and Physical Documentation Limits

The seller documents the internal mechanism as an automatic mechanical Calibre 6159a with a reported 72-hour power reserve, though the movement jewel count is recorded as unknown. Because no internal or uncased movement photographs are provided, the caliber and its mechanical state remain strictly seller-reported.

The date of issue is listed as 1975, but no individual serial number is recorded in the source text. In addition, the seller explicitly notes that the watch includes neither original presentation box nor paperwork.

Evidence for this section
  • “Calibre 6159a”
  • “Power reserve 72 Hours”
  • “Box/Papers No/No”
  • “Date of issue 1975”

Open research questions

  • What specific caseback serial number or reference markings are stamped on this specific watch to verify its production date?
  • Can physical inspection or movement photographs confirm the presence, condition, and jewel count of Calibre 6159a?
  • Does inspection confirm whether the strap and shroud screws are original factory components or later replacements?

Source evidence

Recorded claims and source quotations for Seiko 'Grandfather Tuna' Professional 600 Diver
FieldSource-reported valueSource quotation
Model Reference6159-7010“Model Ref: 6159-7010”
Case MaterialTitanium“Case Titanium”
CalibreCalibre 6159a“Calibre 6159a”
Case Width50.5mm“Width (without crown) 50.5mm”
Lug Width22mm“Lug width 22mm”
Reported Lug Height50mm“Lug height (lug to lug) 50mm”
Reported CrystalMineral“Crystal Mineral”
Reported StrapOriginal Seiko Rubber“Bracelet Original Seiko Rubber”

Visible details

  • Protective dark shroud encircles the case perimeter, fastened by exposed screws
  • Dial text reads 'SEIKO / AUTOMATIC' below 12 o'clock and 'PROFESSIONAL / 600' above 6 o'clock without an 'm'
  • Offset grooved crown positioned near 4 o'clock
  • Black rotating bezel with calibrated minute markings and a luminous triangle at 12 o'clock
  • Black dial with circular luminescent indices, triangular 12 o'clock marker, lollipop seconds hand, and date aperture at 3 o'clock

Research qualifications

  • Internal movement caliber 6159a is seller-reported and not directly visible in the image
  • Titanium case construction is reported by the seller but not verified through caseback inspection in the photograph
  • Neither original box nor papers are included per the seller

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

Consulted source

Seiko - A Vintage Grandfather Tuna Professional 600 Diver Titanium - M – Vintage Watch Specialist

Reviewed 2026-10-21 · Record e3eeb50e19

Terms in this record

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

Other diver's wristwatch records