The Bronze Field Guide

San Martin SN003-Q Bronze Tuna

The San Martin SN003-Q Bronze Tuna is a current-production diver watch with a cusn8 bronze case. It measures 42.0 mm across, 15.2 mm thick, and is water resistant to 300 m. Inside is the NH36 seiko nh36 automatic movement, with 41 hours power reserve. Complications: Date. Priced from $250 (approx). Brand origin: China.

Bronze diver watchesCuSn8Skin-safe backDiversUnder $500
Reference
–
Type
Diver
Price
$250 · approx
Case diameter
42.0 mm
Thickness
15.2 mm
Lug-to-lug
–
Water resistance
300 m
Weight
–
Origin
China
Movement
Seiko NH36 automatic
Caliber
NH36
Power reserve
41 hours
Complications
Date
Ceramic
CuSn8 marine bronze
Colour
–
Hardness
–
Construction
Assembled
Surface treatment
–
Caseback
Steel
Nickel-free
No (steel contact)
Bracelet / strap
Rubber strap
Ceramic bracelet
–
Crystal
Sapphire
Display back
No
Dial
Multiple dial colours
Lume
SuperLuminova
Availability
Offered
Status
Current
High confidence Verified Jul 2026 Source: SKB Watches Maker / listing ↗
Facts are free to cite with a link.
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Frequently asked questions

Is the San Martin SN003-Q Bronze Tuna nickel-free?

No. At least one part that touches the skin is nickel-bearing steel (commonly the caseback or clasp), so the guide does not mark it nickel-free.

What bronze alloy is the San Martin SN003-Q Bronze Tuna?

The San Martin SN003-Q Bronze Tuna has a cusn8 bronze case, though its caseback is steel. This is confirmed against the maker spec.

What size is the San Martin SN003-Q Bronze Tuna?

It is 42.0 mm in diameter, 15.2 mm thick, and water resistant to 300 m.

How much does the San Martin SN003-Q Bronze Tuna cost, and is it available?

It is current-production and lists from $250.

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