San Martin SN0138 37mm Vintage Dive Watch — ST2130, Snowflake Hands, Aluminum Bezel, 200m

The San Martin SN0138 is a 37mm vintage-character dive watch powered by the Seagull ST2130 high-beat automatic movement at 28,800 vph. It is San Martin’s most compact serious dive watch — 37mm diameter, 45.8mm lug-to-lug, 200m rated — built around a coherent set of vintage dive watch design decisions: a GS Crafts snowflake hour hand with lollipop seconds, a 120-click bead-blasted aluminum bezel, applied three-dimensional indices with lume fill, and a sapphire caseback displaying the ST2130 movement.

Seven colour variants are available, including three limited editions. Two lume systems are offered depending on the variant — C3 green or BGW-X1 blue-white.

Key Specifications

Seven Variants — Colour and Lume Guide

Retro Matte Black / C3 lume: Black matte dial with gold-toned applied indices and snowflake/lollipop handset in gold. C3 green lume emission. The gold-on-black combination is the most traditionally vintage configuration — consistent with mid-century professional dive watch aesthetics. This is the variant shown in the close-up detail images.

Matte Black / BGW-X1 lume: Same black matte dial with silver-toned indices and handset, BGW-X1 blue-white lume emission. A cooler, more modern read on the same design for buyers who prefer blue-white lume over C3 green.

Matte Blue / BGW-X1 lume: Blue matte dial with matching blue bezel, silver handset, BGW-X1 lume. The matching bezel and dial create a cohesive deep-blue sport watch character. One of the more contemporary-reading configurations in the range.

Matte Red / BGW-X1 lume: Red matte dial with matching red bezel, silver handset. The matte finish controls the tone — the red reads as assertive and distinctive without being garish on the wrist.

Limited Edition Matte Green / C3 lume: Deep teal-green dial with matching green bezel, gold-toned handset and indices, C3 lume. The teal shifts from darker at the centre to lighter at the edges. One of the two limited edition variants — produced in smaller quantities and may not be restocked once sold out.

Limited Edition Matte Purple / C3 lume: Deep purple matte dial with matching purple bezel, C3 lume. Purple in a serious dive watch is rare at any price point — this is the most distinctive collector configuration in the range. The second limited edition variant.

Brown 3D Waffle Dial / C3 lume: The most textured variant — a three-dimensional waffle grid pattern on the brown dial surface rather than a flat matte finish. Pairs with C3 green lume. The most overtly vintage-character dial in the seven-variant lineup.

The Design — What Distinguishes the SN0138

GS Crafts Snowflake Hour Hand and Lollipop Seconds

The snowflake hour hand is one of the most recognisable vintage dive watch hand designs — a wide, cutout profile that maximises lume surface area while creating an immediately identifiable silhouette. The “snowflake” designation comes from the hand’s appearance when viewed straight on: a broad frame with characteristic openings that give it a multi-lobed shape no standard sword or baton hand replicates.

On the SN0138 the snowflake frame is polished (gold-toned on the retro black variant, silver-toned on others) with the lume cell sitting precisely within the frame. The close-up dial images show the lume fill flush with the hand surface and the outer frame catching light from its polished edges — a finishing detail that reads as considerably more expensive than the price suggests.

The lollipop seconds hand pairs with the snowflake: a slim stem with a circular lume ball at the tip. The circular head sits visibly above the dial plane, clearly distinguishable from the hour and minute hands at a glance — a practical dive watch design choice from the same vintage professional watch vocabulary.

Bead-Blasted Aluminum Bezel

The bead-blasted aluminum bezel creates a fine, uniform matte surface texture by propelling small glass or ceramic beads against the metal during finishing. Unlike polished ceramic — which reflects light clearly — bead-blasted aluminum has a soft, granular appearance that catches ambient light at low angles and reads as matte from most angles. The visual effect is period-correct for a vintage dive watch: professional instruments of the 1950s–1970s used matte surfaces to reduce reflective glare.

Aluminum develops a subtle patina over time with regular use — the surface will soften slightly and develop the character of a worn professional tool. Buyers who want a bezel that maintains a permanent factory appearance should choose ceramic; buyers who want the vintage aging character should choose the SN0138.

The 120-click bezel provides 30-second increment resolution — more precise than the standard 60-click, one-minute-per-click format.

The bezel triangle marker shows a red triangle with a gold-rimmed luminous dot sitting within it — a detail visible at close inspection that adds depth to what at a distance reads as a simple bezel marker.

Applied 3D Indices

Each index on the SN0138 dial is physically applied — raised above the dial surface as a separate component rather than printed. The rectangular markers at 3, 6 and 9, the triangular markers at the intermediate positions, and the circular dot indices at each hour position are all individually fixed to the dial plate. At close range each index casts a micro-shadow on the dial surface beneath it — the kind of three-dimensional depth that printed dials cannot create.

The applied San Martin hexagonal brand medallion on the dial is also three-dimensional — a raised, gold-tone element with machined letter detail that confirms the brand mark is applied rather than printed.

The ST2130 Movement

The Seagull ST2130 beats at 28,800 vph — 8 steps per second, producing a noticeably smoother seconds sweep than the 21,600 vph Seiko NH35 used in many comparable dive watches. It hacks and hand-winds. Power reserve is approximately 42 hours.

At 28,800 vph the sweep quality is visible both on the wrist and through the sapphire caseback. The caseback reveals the ST2130 rotor and movement bridge with concentric-circle finishing on the main plate and the Seagull-logo rotor decoration. For a 37mm watch with a vintage aesthetic, the high-beat movement architecture adds a technical depth appropriate to the overall specification.

For a detailed comparison of ST2130 against the NH35, SW200 and other calibers in the San Martin and Baltany ranges, see the Baltany Movements Guide — the ST2130 specifications apply across both brands.

The 37mm Case — Why It Matters

The SN0138’s 37mm diameter is a deliberate choice. The dive watch market has standardised around 39–42mm over the past two decades, leaving buyers with smaller wrists, buyers who prefer period-correct vintage sizing, or buyers who find larger cases uncomfortable without serious options from brands who build dive watches properly.

At 37mm with a 45.8mm lug-to-lug, the SN0138 fits wrists from approximately 6 inches (15cm) upward without the lug ends extending past the wrist edges. It sits within a slim footprint under a shirt cuff. It carries the visual proportions of a 1960s professional dive instrument.

The 200m water resistance, screw-down crown and caseback, and 120-click bezel are identical to larger watches in the San Martin dive range. The size is an aesthetic and ergonomic decision, not a technical compromise.

On-The-Fly Adjustable Clasp

The OTF clasp allows micro-adjustment while the watch is on the wrist without tools — push the button and the bracelet extends or contracts in approximately 2mm increments. Useful for wrists that change with temperature, for wearing over a sleeve, or simply for dialling in a precise fit without sitting down with a pin tool.

The clasp face carries the San Martin 3D hexagon logo matching the crown, maintaining brand detail consistency across every hardware element.

The SN0138 in the San Martin Dive Range

The SN0138 occupies a specific position within San Martin’s dive watch lineup:

San Martin SN0138 (this watch): 37mm, ST2130 high-beat, snowflake/lollipop handset, aluminum bezel, 7 colour variants. The compact vintage diver for wrists under 7 inches or buyers who specifically want the vintage aesthetic at period-correct sizing.

San Martin 62MAS 37mm: Also 37mm — the parallel compact option with a different dial character. Compare directly if you want the 37mm format without the snowflake handset.

San Martin BB58: 40mm, NH35, vintage diver character. Three millimetres larger with the Seiko movement rather than Seagull ST2130. For buyers who want the SN0138’s vintage character in a slightly larger case.

San Martin SN0007 62MAS 39mm: 39mm, NH35, enamel dial, historical reference design. The mid-size historically-referenced vintage diver option.

San Martin SN0136 GMT: 39mm, NH34 GMT, sunray enamel dial. The GMT complication option for buyers who want travel functionality alongside dive specification.

FAQ

What is the snowflake hour hand? The GS Crafts snowflake is a vintage-style dive watch hand with a wide, cutout frame that maximises the lume surface area. The name comes from the hand’s multi-lobed shape when viewed from the front. It pairs with the lollipop seconds hand — a slim rod with a circular lume ball at the tip.

What is the difference between C3 and BGW-X1 lume? C3 Super-LumiNova emits green light in darkness — the traditional dive watch lume colour standard since the move away from radium. BGW-X1 emits blue-white light — a cooler, brighter tone. C3 is on the retro black, limited green, limited purple, and waffle brown variants; BGW-X1 is on the standard black, blue, and red variants. Choose based on your lume colour preference.

What is a bead-blasted bezel? Bead blasting creates a fine, uniform matte surface texture. Unlike ceramic which reflects light clearly, bead-blasted aluminum has a soft, granular appearance that reads as vintage and develops subtle patina over time.

Why 37mm for a dive watch? 37mm reflects the actual case sizes used on professional dive watches through the 1950s–1960s before industry convention shifted upward. At 37mm the SN0138 has period-correct proportions, fits smaller wrists properly, and sits under a shirt cuff without catching fabric. The 200m specification is identical to larger models.

Are the limited editions genuinely limited? San Martin designates matte green and matte purple as limited editions produced in smaller quantities. Once sold out they may not be restocked. If either is your specific reason for purchasing, confirm stock availability before delay.

More from Jewelry Addicts

• San Martin BB58 40mm Vintage Diver — the 40mm vintage diver sibling
• San Martin SN0136 39mm GMT Diver — GMT complication on a dive case
• San Martin 62MAS 37mm — parallel 37mm option
• San Martin SN0007 62MAS 39mm — historically-referenced 39mm vintage diver
• San Martin Watches — Full Collection — all San Martin models at Jewelry Addicts