Grand Seiko 200m Spring Drive diver’s watch reference materials. SBGA461 and SBGA463

Grand Seiko’s Spring Drive 200m diving watch has always been admired for its accuracy and robustness. Now, according to ISO Standard 6425:2018, the in-depth readability is further enhanced by including Lumibrite time scales in all 12-hour time scales, including the time scale at the three o’clock position on the right side of the calendar frame.

SBGA461 and SBGA463 are made of stainless steel and high-strength titanium, respectively. High-strength titanium provides higher scratch resistance and corrosion resistance, and significantly reduces weight (about 30%) than stainless steel. Regardless of the metal material used, both watch cases have been refined. The contrasting hairline and Zaratsu polished surface demonstrate Grand Seiko’s strict attention to detail.

The diameter of the case is 44.2 mm, the thickness is 14 mm, and the length is 50 mm. The waterproof depth is 200 meters, and the magnetic resistance is 4,800 A/m. This iconic diving watch is powered by Grand Seiko’s unique Spring Drive 9R65 movement, which combines the power of the mainspring and the high precision of a quartz watch.

The design of each hand is different, which is clearly visible from the dial, and the triangular mark at the twelve o’clock position ensures that there is no error even in depth. The eye-catching multi-faceted hour markers are fixed on the dial by die forging process to ensure its shock resistance. The dials of both models are matte black, and the hands, markers and bezel are coated with a large amount of LumiBrite to provide nighttime visibility. The bezel inserts have also been slightly redesigned, and the position of each minute is marked. This design has nothing to do with the aforementioned ISO specifications, but an internal decision to improve accuracy and legibility.

Every component on these watches is durable, but divers know that their watches require regular maintenance, just like all other equipment they rely on during their activities. Therefore, the case and bezel (in a four-part design) are designed for safe disassembly and reassembly during routine inspections at the copy Grand Seiko Service Center. In addition, the area around the crown has been carefully designed to ensure that residues in dirt, sand or sea water can be easily washed away after use. Both models are paired with a matching five-piece bracelet with a ratcheting diver extension on the buckle.