Arguably the most ubiquitous, yet still desirable Seiko divers watch of the past 35 years is the 6309-7040, the successor to the 6105 duo and produced from the late 1970’s to the mid-1980’s. While the newer watch retained the 150m water resistance of its predecessors, it added a screw-down crown and day/date complications to the movement. The 6309A is a very robust and very good 17 jewel automatic movement used widely by Seiko in both this application but also in numerous dressier models. It is perhaps not quite as high a quality movement as the 6105 but still much nicer than the 7002 and 7S26 movements that were used in the mainstream 200m divers produced from the early 1990’s through to present day.
The great appeal of the 6309-7040 lies in its beautiful, symmetric cushion case and in the classic dial and hand design. The dial features printed hour indexes rather than the embossed indexes of the 6105 but this is the only really obvious quality compromise with the watch in the hand (although of course a printed dial does not necessarily mean cheap!). These watches are in plentiful supply but unfortunately the majority have had dials, hands and inserts replaced by poor quality reproductions. The aftermarket dials in particular pale by comparison to a good condition original and are quite easy to spot, most notably from the quality of the printed text on the dial and the lack of bevel around the day/date aperture.
I’ve had several through my hands in the past two to three years, the best of which came from Australia with a very good original dial but with greyed lume from moisture ingress. I elected to have the dial and hands relumed while servicing the movement myself – one of my earliest attempts at a full movement service.
The second example worth reporting here was a much scruffier watch requiring a lot of attention. This one came with aftermarket everything and the first job was to replace the dial with a second hand, original Suwa dial and better quality hands. I also elected to replace the movement with a 21 jewel hacking 6306A taken from a rather poorly Japanese market Silverwave.
With movement, dial and hands replaced all that remained was to substitute the bezel insert with one of the higher quality aftermarket inserts available and to replace the crystal with one designed for the 6105 divers. The original watches have perfectly flat crystals but the addition of a domed crystal is a popular modification that I think enhances the appearance of the watch. You will notice I made the same change to the first watch above.