Heimdallr 6105 Bronze Automatic Dive Watch — NH35, CUSN8, 200m, Super C3 Lume

Heimdallr 6105 Bronze Automatic Dive Watch — NH35, CUSN8, 200m, Super C3 Lume

The Heimdallr HMCC21 is a 45mm solid CUSN8 bronze automatic dive watch — a cushion case profile powered by the Seiko NH35 automatic movement, with a rotating bronze bezel, Super C3 luminous markers and hands, AR-coated sapphire crystal, screw-down crown and caseback, 200m water resistance and brown leather strap with bronze buckle. Available in black, green and blue dials.

The CUSN8 bronze case develops a natural patina through contact with air, moisture and skin — the watch changes appearance over time in a way unique to each owner.

Key Specifications

Variants — Three Dial Configurations

Black: High contrast — white or cream luminous markers and hands on a black dial field. The most legible underwater and in low light. The classic dive watch combination; the bronze case against a black dial creates the strongest visual contrast.

Green: A green dial against the warm bronze case — the two warm tones create a cohesive and organic character. Green dials on bronze cases are specifically popular in the bronze dive watch collector community.

Blue: A blue dial against the bronze case creates a cool-warm contrast — the blue reads distinctly against the amber-bronze tones, producing the most colour-dynamic of the three combinations.

CUSN8 Bronze — What It Is and How It Ages

CUSN8 is a copper-tin alloy — approximately 92% copper and 8% tin. The “tin bronze” designation distinguishes it from brass (copper-zinc) and other alloys. CUSN8 is specifically chosen for dive watches because:

Corrosion resistance: The tin content creates an oxide layer that protects the underlying metal from further corrosion in marine environments — unlike iron-based metals, bronze does not rust. The oxide layer is the patina itself.

Natural patina development: The copper content reacts with oxygen, moisture, skin oils and environmental exposure over months and years. The surface darkens from bright golden-orange toward warm brown, chocolate or greenish tones depending on exposure history. High-humidity environments, salty air and active wear accelerate patina development. Areas of contact — the case sides, lug edges, bezel edges — develop faster than sheltered surfaces.

No two alike: Because patina develops through the specific environmental and wear history of each watch, no two bronze watches aged the same way will look the same. After two years of wear, the HMCC21 will have a surface character unique to its owner.

Reversing patina: If the patina is unwanted, the bronze can be polished back to bright. Most owners prefer to allow the patina to develop naturally.

Cushion Case — The 6105 Profile

The “6105” designation references the cushion case profile — a rounded square or pillow shape where the case sides bow outward rather than meeting at right angles. The cushion profile distributes the case’s surface across the wrist differently from a round case, sitting broader and flatter. On a 45mm case the cushion creates a large dial presence without feeling as heavy as a 45mm round case of equivalent diameter.

The 46.8mm lug-to-lug is compact relative to the 45mm case width — the short lugs keep the watch from extending too far beyond the wrist edges despite the large case diameter.

Super C3 Luminous

Super C3 is a grade of Super-LumiNova phosphorescent material — it absorbs visible and UV light and re-emits it as green glow in darkness. The “Super C3” designation indicates a high-output grade of the material. On a dive watch, lume quality directly affects underwater readability in low-visibility conditions. Large applied markers and oversized hands maximise the lume surface area on the HMCC21 dial.

200m — Full Dive Specification

200m / 20 ATM is a genuine dive watch water resistance rating. The screw-down crown and screw-down caseback both contribute to sealing the case under pressure. At 200m the watch is rated for:

• Swimming
• Snorkelling
• Recreational scuba diving (typically to 40m/130ft for recreational divers)
• Freediving to moderate depths

The rotating bronze bezel provides elapsed time measurement — align the 0/12 marker with the minute hand at dive entry to track elapsed time as the minute hand advances.

Bronze vs Stainless Steel Dive Watch — The Trade-Off

Bronze advantages: Unique patina development, distinctive warm visual character, corrosion resistance in marine environments, rarity relative to steel.

Bronze considerations: Heavier than equivalent titanium cases. Patina can transfer faint colour to light-coloured shirt cuffs during early development phases. The case cannot be polished to the mirror-bright finish of stainless steel once patina has developed on flat surfaces.

For buyers who have only owned stainless steel watches, the HMCC21 is a fundamentally different ownership experience — a watch that changes rather than one that maintains a static appearance.

Who Is the Heimdallr HMCC21 For?

The HMCC21 is built for:

• Bronze dive watch buyers who want CUSN8 construction with NH35 reliability at 200m
• Patina collectors who specifically want a watch that develops unique surface character over time
• Green dial bronze buyers — the green/bronze combination is the most popular pairing in the collector community
• Cushion case buyers who want the 6105-profile architecture in bronze at an accessible NH35 price

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