SKX013 Diver 38 Green Ultra Thin Edition — front view with cyclops lens magnifying the date window position

SKX013 Diver 38 Green Ultra Thin Edition — three-quarter angle view facing right, showing green ceramic bezel insert with BGW9 lume pip

SKX013 Diver 38 Green Ultra Thin Edition — front view, no cyclops lens, 38mm dive case for NH movements

SKX013 Diver 38 Green — Ultra Thin Watch Case

SKX013 Diver 38 Black Ultra Thin Edition — vernier caliper measurement showing 10.856mm case thickness

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SKX013 Diver 38 Green — Ultra Thin Watch Case

Name: SKX013 Diver 38 Green — Ultra Thin Watch Case
Brand: Lucius Atelier
SKU: Sub38UT.Green/UT.Solid/Cyc
Price: 249.0 SGD
Availability: InStock

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$239 SGD - $274 SGD

Caseback

Ultra Thin Solid sold out

Thick Solid sold out

Sapphire

Cyclops Lens

Yes

Worldwide
Delivery Express
2–4 Days Replies In
1 Day 30-Day
Returns

SKX013 Diver 38 Green Ultra Thin on mossy stone in tropical jungle stream

The Sub Silhouette. Reborn Ultra Thin. Ready to Build.

Inspired by the dive-watch silhouette that defined an era, the SKX013 Diver 38, part of our Ultra Thin Edition series, is our ground-up reinterpretation — engineered to be among the thinnest dive cases compatible with the NH movement on the market today.

Achieving this profile meant rebuilding the case body from scratch. Every internal dimension was re-engineered to compress the case height without compromising structure. As a consequence, the bezel, ceramic insert, and sapphire crystal are unique to this case — standard SKX bezels, inserts, and crystals will not fit, and ours will not fit a stock SKX. All three ship pre-fitted and aligned at our workshop. They can be removed by a watchmaker, but the design and parts are exclusive to us.

What we did keep compatible: the things modders actually want flexibility on. SKX-style crowns, SKX013-spec chapter ring, Seiko Mod dials (28.5mm), hands, and NH-series movements all work as expected. You get the thinnest dive-style profile on the market, paired with the modding ecosystem you already know.

Roughly 10% cheaper than building it part-by-part — and ready to assemble.
Buying our SKX-style case body, matching bezel, ceramic insert, and sapphire crystal separately would cost about 10% more than this complete case. And you skip the hardest parts of the build: no crystal-pressing the sapphire, no fitting the rotating bezel, no sticking and aligning the ceramic insert. We ship it pre-fitted and pre-aligned. For a dive-style build with a rotating ceramic bezel, that's hours of finicky workshop time avoided.

Wears 38, looks bigger.
Case diameter 38mm. With crown guards the case width reaches 40mm. Lug-to-lug 46mm, lug width 20mm. A diver's silhouette on a small-wrist canvas. See how we measured it against a 42.5mm SKX007 .

Genuinely thin.
10.86mm with the Ultra Thin solid caseback — one of the thinnest NH-compatible dive cases ever made. The NH movement alone is 7.59mm. That leaves just a few millimeters for the crystal, walls, and hand clearance. Tight engineering.

Built to dive (when you choose to).
Up to 200m water resistance. Screw-down crown. Unidirectional 120-click rotating bezel with green ceramic insert and Swiss Super-LumiNova® BGW9 Grade A lume pip. Bezel and insert ship pre-fitted and pre-aligned.

Three casebacks, two crystals.
Pick the Ultra Thin solid caseback for the headline thinness. Pick the thicker solid caseback for full 200m dive-rating. Pick the sapphire caseback to display the movement — and consider adding a decorated bridge and rotor for a fully customised view through the back. Cyclops crystal pairs with NH35 only — the magnifier sits over the date window, so the dial must have one.

Caseback	Total Thickness	Water Resistance	Best for
Ultra Thin Solid · HEADLINE BUILD	10.86mm	100m / 10 ATM	Daily wear — the thinnest profile
Thick Solid	11.36mm	200m / 20 ATM	Modders who actually take it diving
Sapphire	11.76mm	100m / 10 ATM	Movement display — show off the rotor

The Ultra Thin Solid caseback is the headline build — this is the case at its slimmest. The other two are for buyers prioritising dive-rating or movement display, and add slight thickness in exchange.

Curious what other modders actually chose?

Live · Community Build Data

What modders actually choose

Every SKX013 Diver 38 build, tallied.

Ceramic Bezel Black 78%Green 22%

Black is the timeless default — where most builds start. Green is the quiet flex, the one that gets the “what is that?”

Caseback Ultra Thin 81%Thick 10%Sapphire 9%

Ultra Thin is the runaway favourite — the slimmest, headline build. Thick trades a little height for a true 200m dive rating; Sapphire opens a window on the movement.

Cyclops Crystal Clean 67%Cyclops 33%

Most keep the crystal clean. A bold minority add the cyclops — the date magnifier, NH35 only.

Heads up — sold separately

Crown. The crown shown in product photos is for visual reference only. Crowns must be selected above — choose from 5 SKX013-compatible options. Browse compatible crowns .

Chapter ring. This case requires a SKX013-spec chapter ring to seat the dial correctly — without it, the dial sits too low and hands won't clear. The case fits both normal and ultra thin chapter rings; the choice depends on your dial, not the case. If your dial has applied (raised) indices, choose ultra thin for clearance. If flat-printed, either works. When in doubt, ultra thin is the safer default. Browse compatible chapter rings .

For experienced modders only — TYPE M movements only

This case fits TYPE M versions of NH35, NH36, NH38, NH70, NH71, NH72 only. TYPE L will NOT fit. Due to tight clearance between hands and sapphire, this case is recommended only for professional watchmakers and experienced modders.

Specs
Build Guide
What's Included
How To Mod

Dimensions
1. Case Diameter 38mm
2. Case Width (with crown guards) 40mm
3. Case Thickness 10.86mm (Ultra Thin Solid) / 11.36mm (Thick Solid, 200m) / 11.76mm (Sapphire)
4. Lug to Lug 46mm
5. Lug Width 20mm
Materials & Finish
1. Quality Swiss Production Quality, ISO 9001 Certified
2. Case Material 316L Stainless Steel
3. Case Finishing Brushed (lug tops), Mirror polished (lug sides)
4. Bezel Unidirectional rotating, 120-click (pre-fitted at workshop, exclusive to this case)
5. Bezel Insert Green ceramic with Swiss Super-LumiNova® BGW9 Grade A lume pip
6. Crystal Flat Sapphire with clear AR coating (cyclops or no-cyclops, per selection; pre-installed, exclusive to this case)
7. Crown Screw down, SKX-style compatible
Compatibility
1. Movements TYPE M: NH35, NH36, NH38, NH70, NH71, NH72
2. Dials 28.5mm
3. Chapter Rings SKX013-spec (required, sold separately)
4. Hands NH movement compatible
5. Crowns 7mm SKX-style
6. Bracelets Lucius Atelier bracelets only (designed exclusively for our cases)
Water Resistance
1. Ultra Thin Solid Caseback 100m / 10 ATM
2. Thick Solid Caseback 200m / 20 ATM
3. Sapphire Caseback 100m / 10 ATM
New to Seiko modding? Here's everything you'll need for a complete, functioning watch — in the order you'd actually assemble it.

What's already in this purchase:

The case body, bezel + ceramic insert (pre-fitted), and your chosen caseback + crystal. That's the foundation. Everything below is what you'll add to make a functioning, wrist-ready watch.

The 5 parts you'll need for a complete watch:
1. Chapter ring — required first. The chapter ring seats the dial at the correct height; without it, the dial sits too low and the hands won't clear.
  (SKX013-spec — sold on a separate page. See the "sold separately" panel above for normal vs ultra thin guidance.)
  Browse compatible chapter rings
2. Crown — five SKX-style options. Pick a style that matches the watch's character.
  (Required to add to cart. Selected from the dropdown above on this page.)
  Browse compatible crowns
3. Dial (28.5mm) — the face of the watch. The biggest aesthetic choice you'll make. Match it to your chosen movement (date / day+date / no-date dial).
4. Hands — paired with your dial. Most modders match lume colour across both hands and dial markers (BGW9 white-blue, C3 green, etc.).
5. Movement — NH35 (date), NH36 (day+date), NH38 (no date), or source your own. The movement is the engine of the watch.
Optional finishing touches:
1. Bracelet or strap (20mm lug) — Lucius Atelier oyster, jubilee, president, GS, Seikonaut, Settimo, or more designs, plus custom shell cordovan / full-grain cowhide leather straps.
2. Decorated bridge + rotor (only visible with sapphire caseback) — replace the stock NH movement bridge and rotor with our Côtes de Genève decorated set, viewable through the sapphire caseback. Note: our bridges fit only our rotors (not OEM Seiko rotors), so they're chosen as a pair. Recommended for experienced modders only — or tick Assemble Watch below and we'll handle it.
Want it built for you?

Tick the Assemble Watch (+SGD $50) option above on this page and we'll handle the full build in our Singapore workshop — case fitting, movement seating, crown alignment, caseback press, function check, and decorated bridge + rotor installation if you've added those.

Heads up: assembled watches require 3–5 business days of workshop time before shipping.

Once your parts arrive, see the How To Mod tab for assembly tutorials.
1. 1x Watch Case Body (with pre-installed flat sapphire crystal — cyclops or no cyclops, per selection)
2. 1x Bezel + Green Ceramic Insert (pre-fitted, pre-aligned, with BGW9 Grade A lume pip)
3. 1x NH Caseback (Ultra Thin Solid / Thick Solid / Sapphire, per selection)
All photos of watches with modification parts are for illustration purposes only and are not included with the case purchase.

Cyclops or no cyclops — and which movement do I need?

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.

Which caseback should I choose?

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.

Why are the bezel, insert, and crystal exclusive to this case?

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.

What is the SKX013 Diver 38 and how does it differ from the original Seiko SKX013?

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.

What's the difference between Type M and Type L?

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.

Do I need to remove the sapphire crystal to install the chapter ring?

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.)

Should I choose the normal or the ultra thin chapter ring?

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.

What is an SKX013 chapter ring and why does it matter?

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.

Does this case need a chapter ring?

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.

Will SKX007 dials fit?

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.