If it came down to owning just one watch, there’s no question that Seiko’s 6309-7040/49 is a strong contender. Still their top selling diver to date, it’s a tool watch so perfectly executed, it remains firmly at the top of our list. Balance, contrast, and contouring all neatly assembled into a finished product that is much greater than the sum of its parts. A bare bones beauty that more than proves that less is in fact, more. Truly, the only Seiko diver we’d prefer more is its JDM brother, the 6306-7000/1. Produced alongside the 6309 from 1976 to early 1981, the 6306 was the JDM variant of Seiko’s third generation 150m dive watch, and offered clear benefits over the export version. The jewel count of 21 is four higher than the 17 jewel export, and the addition of a hacking lever allowed for seconds setting on the 6306. It is otherwise identical except for the day wheel which offers both English and Kanji on the 6306. This example from April of ‘78 is everything a great tool watch should be. The matte black dial is spotless, and carries the Suwa “S” logo above the six o’clock marker. This signifies its earlier production, and that it was built and cased completely in Japan. The hour markers are free degradation or discoloration, and the luminous material has developed a soft and uniform sand patina. The hands have mostly retained their polished finish, but some oxidation is visible, and the luminous material shares a similar patina to the hour markers. The bezel rotates smoothly in either direction with a firm “click,” and the insert bears only minor wear. The case is unpolished, and it’s original finishes are still visible, with only light signs of wear throughout. The case back markings are clear and crisp, and free of tool marring. Both the case back and crown screw down tightly with ample threading. Post service it’s keeping near perfect time, and ready for many more years of reliable service. It comes attached to the original Seiko GL-831 flat vent composite strap with the original keeper for an absolutely original fit and finish. These original straps are highly coveted, and have become nearly impossible to source. Completely original aside from a replacement crystal, it is a true Seiko icon, and a must have for any enthusiast.

Original Seiko GL-831 Flat Vent Black Composite

Serviced 12/23

Diameter- 44mm

Lugs-22mm