SKX013 Diver 38 Black — Ultra Thin Watch Case

The cyclops is a magnifier lens fused to the front sapphire crystal, sitting over the date window at the 3 o'clock position. Choose cyclops only if you're using an NH35 movement — NH35 is the only NH variant in our compatible list with a date complication. NH36 has day+date, NH38 has no date, NH70/71/72 are skeletonized variants. If you pick cyclops with the wrong movement, you'll have a magnifier over a blank dial position. Choose no cyclops for any other NH movement, or simply for a cleaner crystal profile.

The Ultra Thin Solid caseback (10.86mm, 100m WR) is the headline build — this is the case at its thinnest. Choose Thick Solid (11.36mm, 200m WR) if you actually plan to take the watch diving. Choose Sapphire (11.76mm, 100m WR) if you want to display the NH movement and rotor through the back. All three pair with either cyclops or no-cyclops crystal.

To achieve this thinness profile, we re-engineered the case body from scratch — including the internal bezel-seating and crystal-seating geometry. As a result, our bezel, ceramic insert, and sapphire crystal are dimensionally unique. Standard SKX bezels, inserts, and crystals will not fit this case, and ours will not fit a stock SKX. They ship pre-fitted and pre-aligned at our workshop.

The Lucius Atelier SKX013 Diver 38 is a modder's evolution of the form factor Seiko discontinued in 2019. Same 38mm proportions and rotating dive bezel that defined the original, redesigned to Ultra Thin Edition specs (NH-compatible, double-sided AR sapphire pre-installed, ceramic insert in black or green). The original Seiko SKX013 used Hardlex and an aluminium insert; ours uses sapphire and ceramic. It's the smaller-case dive-watch entry point for builders who want vintage proportions with modern materials.

Type M and Type L are Seiko's two factory hand-fitting versions of the NH series. Type L sits higher than Type M — about 0.4mm taller from base to second-hand pinion. Because of the tight clearance between hands and sapphire in Ultra Thin Edition cases, only Type M will fit. Confirm your movement type before ordering.

No — and that's the whole point of us pre-installing the sapphire for you. The chapter ring sits on top of the dial inside the case, not under the crystal, so the crystal stays where it is throughout the build. (If you ever do need to remove the sapphire — for example, to replace it — that's a workshop job we handle for you, not an at-home step.)

The choice depends on your dial, not the case — both sizes fit every Ultra Thin Edition case. If your dial has applied (raised) indices, the ultra thin chapter ring is the better choice because its slimmer profile gives the indices clearance instead of resting on top of them. If your dial is flat-printed (no applied markers), either size works. When in doubt, the ultra thin chapter ring is the safer default because it works with both dial types.

A specific size and spec used by Seiko in the SKX013 (discontinued 2019). The LA smaller-case lineup all uses this same spec, which means dozens of chapter ring designs work across every smaller case in the catalogue.

Any 28.5mm dial will fit. Stock SKX007 dials may seat differently because the original SKX007 has a 4 o'clock crown position with offset dial feet, while Ultra Thin Edition cases are designed for 3 o'clock dial feet.

Yes — every Ultra Thin Edition case requires an SKX013-spec chapter ring, sold separately. The chapter ring seats the dial at the correct height; without it, the dial drops and the hands will not clear properly.

They are rounded off — but they are still crisp, and we would rather say that than have you open the box expecting something softer. "Sharp" is genuinely subjective: a Rolex is sharp too, and where one person reads that as crisp and well-defined, another finds it catches. The bracelet clasp is the sharpest part of the whole package — that is the part to know about before you commit.

If a previous mod was painful to wear, it is worth working out what actually caused it: a poorly finished lug edge digging in is a different problem from a clasp catching on the back of your wrist. Email hello@luciusatelier.com and say which it was, and you will get an honest answer on whether ours will be better or much the same.

Cases ship exactly as listed — no custom machining, no changes to size, lug width or lug shape, no alternative finishes of an existing case, and no engraving (a local engraver or jeweller can engrave a finished part after purchase). What you can customize is the build: choose the case, dial, hands, chapter ring, bezel insert, crystal and bracelet you want and LA will assemble the finished watch for you. Bespoke design work — one-off dials, mockups or renders, designing a build to a brief — is not offered. For fully custom work, see the list of watch modification specialists.

UTE is shorthand for the Ultra Thin Edition — the Lucius Atelier case line engineered to stay near or under 10mm while remaining NH-compatible, where most Seiko mod cases on the market run 13–14mm. It includes the Bauhaus 33mm at 9.93mm with a solid caseback (the thinnest NH-compatible mod case on the market), the Explorer 36mm at 9.96mm, the Seikonaut 38mm at 10.0mm, the NH34 GMT-ready 1908 36mm at 10.75mm, the SKX013 Diver 38 at 10.86mm and the Pilot 34mm at 10.96mm. Ultra Thin cases take the standard 0.4mm dial spec, and both chapter ring sizes fit them.

No — only Lucius Atelier bracelets fit.

A bracelet isn't like a strap. Straps and NATOs hang off plain spring bars, so any 20mm strap works here. A bracelet with solid end-links is a different thing: the end-link is a shaped piece of steel machined to sit flush against one specific case profile. Ours are cut to the Lucius Atelier case shapes — that's what makes them look built-in rather than bolted on.

That precision cuts both ways. An aftermarket or OEM Seiko bracelet was shaped to its own maker's case, not to ours, so it won't sit flush here. The reverse is equally true: our bracelets don't fit generic 20mm lugs or OEM Seiko cases.

Every bracelet in our collection fits this case — including discontinued ones. A bracelet leaving the catalogue only means we stopped making it, never that it stopped fitting. Browse the bracelet collection: https://luciusatelier.com/collections/bracelets

If you'd rather not use a bracelet, any 20mm strap or NATO fits this case.