When Seiko began 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 line in late 1978. Bearing more than a passing resemblance to the 6309-7290, the 7548-7000 shares a nearly 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, one spring driven,  and each as capable as they are impressive. From August of 1982, this no frills tool watch with JDM bonafides, checks all the boxes. It’s completely original, right down the the “Hardlex” crystal that was carefully polished to remove most blemishes. The dial is a spotless matte black with large luminous plots, and the hour and minute hands are familiar carry overs from its predecessors. The second hand, however, is a black and white reverse “lollipop” with a large luminous pip at the end of the tail. The bezel rotates smoothly with a firm click in either direction, and the insert bears only a few small wear marks. The case is unpolished with crisp corners, and the factory finishes are still quite sharp. The crown and case back screw down tightly with ample threading to protect the freshly serviced 7548. It offers independent quickset of both the day (Eng/Kanji) and date, hacking seconds, and with a new battery installed, it’s keeping perfect time. We’ve paired it with a Seiko Z-22 flat vent for a comfortable fit and finish that closely resembles the original . A Seiko diving first with a JDM pedigree, it’s sure to be a fast favorite in any rotation. 

Seiko Z-22 Flat Vent Black Composite Strap

Serviced- 5/26

Diameter- 42mm

Lugs- 22mm