Seikonaut 40mm Case – Gold
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- Genuine 316L Steel & Sapphire
The Yellow Gold Seikonaut delivers the boldest warm-tone finish in the lineup with a full gold PVD coating over 316L stainless steel. At 9.95 mm with a solid caseback, this 40 mm case keeps the ultra-thin Nautilus silhouette while making a deliberate visual statement. The brushed and polished gold surfaces catch light from every angle, and the sapphire crystal is available with clear or blue AR coating. With a screw-down crown rated to 50 m water resistance and compatibility with all NH-family movements and 30.8 mm dials, this case is for builders who want their Nautilus mod to command attention.
Specifications
| Specification | Value |
|---|---|
| Diameter | 40 mm (10H–4H) × 38 mm (12H–6H) |
| Thickness | 9.95 mm (solid caseback) / 10.3 mm (exhibition caseback) |
| Material | 316L Stainless Steel with gold PVD |
| Finish | Brushed and polished gold |
| Crystal | Sapphire (clear or blue AR coating) |
| Water Resistance | 50 m |
| Dial Fit | 30.8 mm |
| Crown | Screw-down, included |
Compatibility
Movements: NH35, NH36, NH38, NH70, NH71, NH72 — all standard Seiko NH-family automatics fit without modification. The crown stem must be cut to length during installation.
Dials: 30.8 mm dials only. Gold and champagne dials create a monochromatic luxury look. Black, dark green, and navy dials provide striking contrast against the gold case. White dials give a clean, classic two-tone feel.
Strap/Bracelet: Compatible with the Seikonaut integrated bracelet in gold. Standard spring bar attachment at the lugs. Black and dark green rubber straps also pair well with the gold case.
Not compatible: 7S26 and 7S36 movements use a different stem height and are not recommended for this case.
What’s Included
- Seikonaut case body (316L steel, gold PVD coating)
- Caseback (solid or exhibition, depending on variant selected)
- Screw-down crown with signed logo
- Crystal gasket and caseback gasket
- Sapphire crystal (pre-installed, clear or blue AR coating)
Tools are not included. You will need a case opener, hand press, stem cutter, movement holder, and rodico to complete your build.
Why We Chose This Case
A full gold Nautilus is one of the most iconic references in watchmaking, and builders have been asking for a gold Seikonaut since the silver version launched. The challenge with gold PVD cases in the mod market is that most look cheap — the tone is too yellow, the finish is too uniform, or the case is too thick to carry the gold aesthetic convincingly. The Seikonaut gold addresses all three issues: the PVD shade is tuned to a warm but restrained yellow gold, the brushed-and-polished finishing adds the surface variety that genuine gold watches have, and the 9.95 mm thickness avoids the chunky look that undermines most gold mod cases. The result reads like a gold sports watch, not a gold-painted mod.
Build Guide
Difficulty: Moderate — suitable for first-time builders with proper tools and patience.
Tools needed: Case opener (or case press), hand press or hand setting tool, stem cutter, movement holder, rodico, and tweezers.
Gold PVD tips:
- Handle with care during assembly: Gold PVD is durable in daily wear but can be scratched by steel tools during the build process. Use rodico and plastic tweezers wherever possible to protect the case finish.
- Stem cutting: Measure twice, cut once. Leave 0.5 mm extra and trim down gradually. A stem that is too short means the crown will not engage.
- Gasket seating: Both the crystal gasket and caseback gasket must sit flat in their channels. A twisted or pinched gasket will compromise the 50 m water resistance rating.
For full step-by-step instructions, see our complete Seiko mod build guide.
Frequently Asked Questions
Is the gold case real gold?
No. The case is 316L stainless steel with a PVD gold coating. PVD (Physical Vapor Deposition) is more durable and scratch-resistant than traditional gold plating. The look is gold-tone, not solid gold, which keeps the price accessible while delivering the visual impact of a full gold watch. The PVD shade is tuned to a warm, restrained yellow gold rather than the overly bright tone found on cheaper alternatives.
Does the gold PVD match the NH72 movement bridges?
Yes, closely. The NH72 skeleton movement has golden-toned bridges, and the Seikonaut gold PVD shade was selected to complement that tone. Pairing this case with the NH72 and an exhibition caseback creates a unified gold build from case to movement bridges.
What strap or bracelet should I use with the gold case?
A gold Seikonaut integrated bracelet creates the full luxury look. For a sportier feel, a black rubber strap provides maximum contrast and lets the gold case take center stage. Green and navy rubber straps also pair well for a bold color-on-gold combination. The lug width is standard, so any 20 mm strap or bracelet will fit.
How thin is this compared to other gold Nautilus mod cases?
At 9.95 mm with a solid caseback, the Gold Seikonaut is one of the thinnest gold Nautilus-style cases available. Most competitors measure 12–14 mm. A thinner gold case reads more like a genuine gold sports watch and less like a plated mod, which is critical for the gold finish to look convincing on the wrist.
Complete Your Build
- Rose Gold Nautilus Skeleton Dial (30.8 mm) — warm-toned skeleton dial for a full gold skeleton build
- Gold V2 Nautilus Hands — matching gold hands to complete the monochromatic look
- Seiko NH35 Movement — reliable automatic movement for a solid gold daily-wear build
- Seiko NH72 Skeleton Movement — golden bridges match the gold case for a unified skeleton aesthetic
- Seiko NH70 Skeleton Movement — open-heart alternative for a partially skeletonized gold build
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Nautilus-Style Seiko Mod Parts · All Seiko Mod Cases · Nautilus Seiko Mods
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