After years of requests to stock the 7548, I decided to get my hands on one and see just what all the fuss was about. It’s just a quartz diver like so many others, right? Actually, just one other... Seiko’s venerable 6309. It turns out, 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 7548-7000 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 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 example from November of 1985 is the North American export variant denoted by the SQ designation on the dial. Like its counterpart, the dial is perfect in matte black with large luminous plots, and the hour and minute hands have been carried over from its predecessor. The second hand, however, is a black and white reverse “lollipop” with a large pip at the end of the tail. The bezel rotates smoothly with a firm click in either direction, and the insert shows moderate, even wear. The crystal is the original hardlex, and with only a few minor hairline blemishes, we opted to forego replacing it. The case is crisp and unpolished with its factory finishes still clearly intact. The crown and case back screw down tightly, and protect the serviced hacking 7548. It is keeping perfect time and has been paired with an aftermarket flat vent strap very similar to the original. Sadly, the original strap could not be salvaged, but I did choose to move the original Seiko tang buckle over to the newer strap. Still a bit under the radar, these early quartz divers are a somewhat available, budget friendly option to add some Seiko diving history to your roster, but as we’ve discovered, the secret is out.

AM Flat Vent Black Rubber Strap with Genuine Seiko Tang Buckle

Serviced 1/13/20

Diameter- 42mm

Lugs- 22mm