Seiko is keeping the candles lit on its 145th anniversary, and this time the Prospex line gets the cake. The Japanese watchmaker just announced the second installment in its 145th anniversary commemorative series: the limited-edition HBB001, a $595 Samurai diver that leans into “Seiko Blue,” the signature shade the brand has been refining since the 1960s.
For a brand that built its reputation on quietly reliable tool watches, anniversary editions are usually less about flash and more about touching up familiar designs with a single, well-chosen detail. That is exactly the play here. Rather than reinventing the Prospex diver, Seiko is using its 145-year milestone as an excuse to highlight the proprietary blue that has shown up across decades of Grand Seiko and Prospex references, dating back to the brand’s first wave of landmark divers and chronographs in the 1960s.
The HBB001 hits a June 2026 release at $595 (€650), matching the price of Seiko’s entry-level Prospex automatics but landing well below the brand’s higher-end Marinemaster and Grand Seiko territory.
Price: $595
Where to Buy: Seiko
Seiko Blue, but make it subtle
Instead of going full blue dial, Seiko uses the color as an accent, splashed onto the two-tone bezel and the seconds hand, paired with a crisp silver-white dial. The result is less “loud diver,” more “clean tool watch you could actually wear with a button-down.”
The case carries over the angular, flat-faced architecture Prospex divers are known for, but in a tighter, slightly downsized package than older Samurai generations. Even the bracelet has been quietly upgraded, with the center links beveled along their edges so they catch light like the case itself rather than reading as a separate, blockier piece.
Dial details and a familiar Samurai silhouette
A closer look reveals more about the design language. The dial carries Seiko’s signature dagger-style hands and distinctly shaped hour markers, both filled with light blue LumiBrite that picks up the Seiko Blue accent in the dark. The date window sits at the 4:30 position so it does not interrupt the dial layout, and the bezel insert splits its color story across the 60-minute scale: the first 15 minutes are rendered in muted silver, the part of the dial divers actually need to read at a glance, while the remaining 45 minutes are wrapped in deep Seiko Blue.
Enthusiasts will recognize the case shape immediately. The HBB001 follows the silhouette of Seiko’s updated SRPL “Samurai” line, a more compact take on the original Samurai that has built a cult following since its first run more than a decade ago. The sharply faceted lugs and broad, flat case surfaces remain, and that visual identity now carries through to the matching hands, indices, and bracelet links for a watch that telegraphs intent before you even read the dial.
Part of a bigger anniversary lineup
The HBB001 is not flying solo. Seiko has been rolling out 145th anniversary pieces across its catalog throughout 2026, starting in February with commemorative King Seiko, Prospex, Presage, and Astron releases anchored by gold-tone accents meant to evoke prosperity and longevity. The Prospex divers are the second wave, and they shift the visual theme from gold to Seiko Blue. The HBB001 has a companion in this set: the HBC005, a 1965 Heritage Diver reinterpretation that shares the blue-and-silver color story but rides on a smaller, vintage-styled 40mm case (13mm thick, 46.4mm lug-to-lug) with 300m of water resistance and the higher-end Caliber 6R55 (72-hour reserve, rated at -15 to +25 seconds per day). It is limited to 4,000 pieces at $1,400 (€1,500).
Together, the two divers cover both ends of the modern Prospex playbook: a vintage-leaning heritage piece for collectors chasing the brand’s 1965 dive watch DNA, and a more aggressive Samurai-style tool watch for buyers who want anniversary cachet without stepping up to four-figure money.
HBB001 specs: 4R35 movement, 41.7mm case, 200m water resistance
Under the hood, the HBB001 runs Seiko’s familiar Caliber 4R35, an automatic movement with manual winding, 23 jewels, a stop-seconds function, a date display, and roughly 41 hours of power reserve. The stainless steel case measures 41.7mm in diameter, 12.3mm thick, and 49.5mm lug-to-lug, with a 20mm lug width feeding into a three-fold bracelet clasp that includes a secure lock, a push-button release, and a diver’s extender.
Dive credentials are solid for the price: 200m (660ft) of water resistance, a unidirectional rotating bezel, a screw-down crown, and a screw case back stamped with “LIMITED EDITION.” Seiko protects the dial with a Hardlex crystal, applies LumiBrite to the hands, indices, and bezel for nighttime legibility, and rates the watch to 4,800 A/m of magnetic resistance. All in, it tips the scales at a substantial 170 grams.
The 4R35 itself has a long backstory worth noting. Introduced around 2010 as part of Seiko’s 4R family, it builds directly on the venerable 7S26 found in countless early SKX divers, adding hacking seconds and manual winding to that proven platform. Its 21,600 vph beat rate and -35 to +45 seconds per day factory rating are not chasing chronometer territory, but the caliber has earned a reputation as one of the most serviceable, durable workhorses in the affordable mechanical space, which is exactly why Seiko keeps deploying it across Samurai, Mini Turtle, and Baby Turtle references.
Why it matters
At $595, the HBB001 lands right in the sweet spot of Seiko’s enthusiast-friendly Prospex range: automatic, ISO-style 200m diver credentials, and a “LIMITED EDITION” engraving on the case back without crossing into Grand Seiko money. The restrained use of Seiko Blue is also a nice nod for longtime collectors who recognize the shade as a brand signature rather than a marketing gimmick.
Price: $595
Where to Buy: Seiko
Seiko will cap the HBB001 at 9,999 pieces worldwide, with availability starting in June 2026 at Seiko boutiques and select retailers worldwide. That is not exactly scarce by modern limited-edition math, but for a sub-$600 mechanical diver carrying an engraved limited-edition case back and a genuinely well-considered colorway, this is the kind of Samurai variant collectors are likely to chase on the secondary market well after the anniversary year wraps.
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