Phylida 500m Ultra Diver — NH38A, 43.5mm, BGW9, Ceramic Bezel, Sapphire

Phylida 500m Ultra Diver — NH38A, 43.5mm, BGW9, Ceramic Bezel, Sapphire

The Phylida 500m Ultra Diver is a 43.5mm automatic dive watch powered by the Seiko NH38A — the no-date version of the NH-series — presenting a blue-to-black gradient dial with BGW9 Super-LumiNova, 120-click unidirectional ceramic bezel, domed sapphire crystal with AR coating and 500m water resistance with a 16mm total case thickness. Available in sterile (no brand text) and branded dial configurations.

At 43.5mm with a 50mm lug-to-lug and 16mm thickness, this is a large-format tool watch — designed for maximum wrist presence rather than discretion. Not suitable for smaller wrists (below approximately 17cm).

Key Specifications

Variants — Sterile and Branded

Sterile: Clean dial with no brand text — indices, hands and gradient dial only. The sterile specification references professional military and expedition watches where brand identity was removed from the dial face. For buyers who prefer no brand text on the dial and the cleaner visual symmetry that provides.

Branded: Phylida brand text and model information on the dial. For buyers who want brand presence.

The No-Date NH38A — Why It Matters on a Dive Watch

The NH38A is the no-date variant of the Seiko NH-series architecture. On a symmetrical round dial, the absence of a date window at 3 o’clock preserves the complete circular symmetry of the indices — no window interrupts the 3 o’clock marker, and the dial reads as fully balanced.

For dive watch enthusiasts who specifically want a no-date configuration, the NH38A is the correct caliber. The NH35, by contrast, places a date window at 3 that breaks the radial symmetry of the index layout.

The NH38A hacks (seconds stop when the crown is pulled) and hand-winds — the same practical advantages as the NH35 for precise time-setting.

Blue-to-Black Gradient Dial

The dial transitions from deep blue at the outer edge toward near-black at the centre under certain lighting conditions — and in others the gradient reverses, appearing lighter at the centre. The direction and intensity of the gradient depends on the light source angle. The effect creates a three-dimensional visual depth that flat monochrome dials do not have.

The gradient also has a practical dimension — the outer edge of the dial where the elapsed time indices sit is the highest-contrast area for lume markers, while the inner zone where the hands sweep maintains maximum readability.

BGW9 Super-LumiNova

BGW9 is the blue-white formulation of Swiss Super-LumiNova — the highest-intensity standard lume formulation. In ambient light it appears as a bright cool white; in darkness it emits a bright, saturated blue-white glow. BGW9 is the formulation used on professional dive watch markers because it provides the highest lume output for underwater visibility.

On the 500m Ultra Diver the BGW9 fills the oversized indices — large enough to provide substantial lume surface area — and the hands. The combination of large index size and high-output BGW9 produces lume performance that is among the strongest in the Phylida range.

500m Water Resistance

500m / 50 ATM is significantly beyond the recreational dive standard of 200m. The additional depth rating comes from a thicker case construction, more robust crown seal specification and stronger caseback engagement — all of which contribute to the 16mm total case thickness. For recreational swimming and diving to typical recreational limits (30–40m), 500m represents a substantial safety margin.

The case dimensions — 43.5mm diameter, 16mm thickness, 50mm lug-to-lug — are directly related to the 500m construction requirement. The case walls and crystal are built to withstand 50 atmospheres of pressure; this requires more material than a 200m case needs.

120-Click Ceramic Bezel

120-click ceramic: 6-degree increment steps allowing 30-second elapsed time resolution. Ceramic at approximately 1,200–1,400HV maintains marking integrity through extended daily wear. Unidirectional rotation — clockwise displacement can only under-indicate elapsed time, preventing decompression risk from accidental bezel movement during diving.

Case Size — 43.5mm Is Large

The 43.5mm case with 50mm lug-to-lug is a large watch. On a wrist below 17cm circumference the lugs will extend past the wrist edge — the case is simply proportioned for larger wrists. For buyers who want the 500m Ultra Diver specification in a smaller case, the Phylida 500m NH35 version may offer different dimensions.

How It Compares in the Phylida Range

vs. Phylida Blue Wave SE-11 — The SE-11 is 41mm at 200m with Miyota 8215. The 500m Ultra Diver steps up to 500m, NH38A with no-date and 43.5mm. Choose SE-11 for more wearable proportions; choose the 500m for maximum specification and wrist presence.

vs. Phylida 500m NH35 — The NH35 version adds a date display at the cost of dial symmetry. The NH38A version is the no-date clean-dial option. Same 500m depth rating.

vs. Phylida 500m Mens Automatic — Compare both directly for case dimensions and dial options. Same 500m specification family.

vs. Phylida SE-32 Aquatica — The SE-32 is 150m — the 500m Ultra Diver is the step up for serious depth specification.

Who Is the Phylida 500m Ultra Diver For?

The 500m Ultra Diver is built for:

• Buyers who specifically want the NH38A no-date configuration for complete dial symmetry
• Large wrist buyers who want maximum case presence — 43.5mm / 50mm lug-to-lug is the boldest Phylida configuration
• BGW9 lume preference buyers who want blue-white lume output rather than warm green
• Sterile dial buyers who want no brand text in the Phylida 500m range

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