When Seiko decided to pursue development of their first core quartz diver, they didn’t have to look far for inspiration. In fact, the 6309 had only been in production for two years when the first 7548’s rolled off the production line in 1978. Bearing more than a passing resemblance to the 6309-7290, the 7548-700X shares an almost identical case, and the bezel, insert, crown, crystal retaining ring, and crystal are all interchangeable between both styles. And if architectural similarities were all there were, it would no doubt be a great watch by default. However, Seiko did as Seiko does, and quite literally built a quartz driven version of the 6309 movement. With the case back removed, one look tells you all you need to know about early Seiko quartz movements. They were not plastic disposable machines to be quickly swapped out at the first sign of trouble, but beautifully, if not overly, engineered movements with jeweled pivots and precisely machined plates. Removing the dial and hands reveals a calendar and keyless works that could easily be mistaken for a 6309. Rather than cousins, these two calibres are brothers. One battery driven, and one spring driven, each as capable as they are impressive. This very early example from July of ‘78 would have been among the first ever produced, and for export as is evident by the “SQ” designation on the lower dial. The dial is everything the pursuit of vintage dive watches should be; a spotless matte blue black with large luminous plots that have developed an all too pleasing sepia toned patina. It’s that special kind of patina that can’t be forced or baked in. Only time and just the right kind of exposure can yield these mouth watering results. The hour and minute hands have been carried over from its predecessor, but here a black and white reverse “lollipop” with a large pip on the tail ticks off the seconds. The bezel rotates smoothly with a firm click in either direction. The “Pepsi” insert shows light wear, but the color fade to vermillion orange and denim blue is everything you didn’t know you needed. The case is crisp and unpolished with its factory finishes still visible. The crown and case back screw down tightly, and protect the freshly serviced, hacking 7548.  It is completely original aside from a replacement mineral crystal, and is keeping perfect time. We’ve paired it with an oxidized GL-831 from Uncle Seiko for a fit and finish as close to the original as possible. Clearly, the secret is out on these 7548 divers, and this one is in a class all its own. Get it while you can.

Uncle Seiko Oxidized “GL-831” Flat Vent Composite

Serviced- 11/23

Diameter- 42mm

Lugs- 22mm