Seiko 'Grandfather Tuna' Professional 600 Diver

Technical characteristics

Type

Diver's watch

Calibre

Calibre 6159a

Lug Width

22mm

Case Width

50.5mm

Case Material

Titanium

Place recorded

Japan

Model Reference

6159-7010

Maker / attribution

Seiko

Design

Visible features

• 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

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.

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.

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.

Identification

Reference

6159-7010

Source note

Facts transcribed from the linked source listing or collection record. Attribution and specifications are source-reported and have not been independently authenticated.

Catalogue references

No catalogue numbers recorded. Numbers are only published once transcribed from a verified edition of a standard catalogue — they are never inferred.