The Seiko SPB143 is a veritable fan favorite among lovers of Seiko dive watches. And that’s for good reason. It combined the mid-range quality we know from this level of Seiko offerings with subtle, timeless dive-watch aesthetics. Today, Seiko releases the spiritual successors to this watch. These are the standard-production SPB451 (blue dial) and SPB453 (black dial) as well as the special-edition SPB455 (with gilt-tone accents). The last one celebrates 100 years of the Seiko name on watch dials.

We will get into all the nitty-gritty below, but let me kick things off with a spoiler: Seiko delivers some subtle updates that add up to make a big difference. I am quite sure these refinements will be welcomed with open arms. Let’s get into it!

Comparing the SPB143 and the new SPB453

The simplest way to get a feel for these new watches is to compare the new black-dial model to the old dark gray one. The first change is the dial itself, which is now truly black. The case has been downsized a little bit — not dramatically, completely changing the watch’s character, but subtly. Consider it a refinement of the fit rather than a true downsizing. The SPB143 measured 40.5mm across, 47.6mm from lug to lug, and 13.3mm thick. The new SPB453 measures 40mm by 46.4mm by 13mm. The bracelet, too, is refined. The links are shorter, as is the clasp.

The changes continue on the inside. The old 6R35 caliber makes way for a 6R55 update. The main difference is the power reserve. While it used to be 70 hours, it is now 72 hours. It’s a negligible difference if not for the fact that it pushes it to three days. And that, my dear Fratelli, is considered worthy of being printed on the dial. I suspect this is the one update that will be unpopular: the dial now mentions: “Automatic 3 Days” rather than just “Automatic.”

The date now sits in a small circular aperture at four-thirty, making room for a full Lumibrite marker at three. The aluminum bezel insert is now laser engraved, to ensure the numerals remain visible forever. Last but not least, the water resistance is now rated at 30 ATM, a marked improvement over the old 20 ATM. This does not typically go hand-in-hand with a thickness reduction, so kudos, Seiko!

Full SPB451, SPB453, and SPB455 specifications

The automatic caliber 6R55 ticks away at a 21,600vph frequency (or six beats per second). This means the seconds hand divides its sweep into three little jumps per second. The caliber retains the jewel count of the old 6R35, at 24 jewels. The movement is hidden behind an all-steel case back featuring the Seiko’s signature wave etching.

The stainless steel case and bracelet both feature Seiko’s proprietary hard coating. This will keep hairline scratches at bay longer in comparison to untreated watches. I have owned a hard-coated Seiko before, and I can attest to it remaining pristine for longer. It will scratch, no doubt, but the accumulation of those tiny hairline scratches, resulting in a haze, happens much more slowly. The clasp features a wetsuit extension and two positions of micro-adjustment. Unfortunately, you will need a tool to adjust it.

You have a choice of three dial variants. There is the aforementioned black SPB453, which I suspect will be the most popular. The second standard model is the blue SPB451. This version features a vivid but dark blue sunray dial. Lastly, there is the commemorative gilt-tone edition.

The special-edition Seiko SPB455

The Seiko company has been around since 1881. It wasn’t until 1924, however, that the name Seiko started appearing on watch dials, so advanced mathematics tells us that Seiko-branded watches have been around for a full century this year. We are spoiled with old companies in the watch world, but it isn’t something to be jaded about. As a business, surviving and thriving for a century is deeply impressive.

Seiko celebrates the fact with a special edition of these new mid-range Prospex divers. The commemorative edition features a taupe sunburst dial with gold-colored details. It exudes a vintage vibe. Specs-wise the watch is completely identical to the standard models. Luckily, this commemorative edition isn’t limited, so you should be able to find one if you want one.

Compared to the standard models, this SPB455 comes with an additional strap. This gray fabric strap is made entirely of recycled plastic bottles through a Japanese weaving technique called Seichu. It is the same technique that is used in traditional kimono cords.

Initial impressions

I have to say that I really like what Seiko offers here. I came close to pulling the trigger on an SPB143 some years back. These are even more tempting. My colleague Nacho had a chance to try the new models on, and he was very positive about the new proportions. In particular, the shorter lug-to-lug will likely make it even more comfortable to wear day in and day out.

The new dial layout works miracles for me too. The date went from prominent to barely noticeable, which I like. The truly black dial is more classically appealing to me compared to the old dark gray. I am less impressed with the “3 Days” on the dial, but it isn’t a dealbreaker.

All in all, I suspect that these will do great for Seiko, not least of all because this segment is drying up. Many alternatives have moved up to higher price segments. Compared to the SPB143, the SPB451 and SPB453 do see a price increase. However, I am happy to report that it is a modest €100 increase to €1,400. Considering all the refinements you get, that could have been much worse. The celebratory SPB455 comes in at €1,600, including the extra strap.

What do you think of the new Seiko SPB451, SPB453, and SPB455? Let us know in the comments below!

Watch specifications

Prospex Diver
SPB451 (blue) / SPB453 (black) / SPB455 (special edition)
Sunray blue/matte black with white printing and silver-tone luminous indices or sunray taupe with gold-tone print and gold-tone luminous indices
Case Material
Stainless steel with ultra-hard coating and aluminum bezel insert
Case Dimensions
40mm (diameter) × 46.4mm (lug-to-lug) × 13mm (thickness)
Curved sapphire with AR coating on the inside
Case Back
Stainless steel with wave etching, screw-in
Seiko 6R55: automatic with hand winding, 21,600vph frequency, 72-hour (three-day) power reserve, 24 jewels
Water Resistance
300m (30 ATM)
Stainless steel three-row bracelet with ultra-hard coating (additional Seichu-weave strap for special edition)
Time (hours, minutes, seconds), date, 60-minute dive bezel
€1,400 (SPB451 and SPB453) / €1,600 (SPB455)
Two years