Full Oystersteel with a smooth bezel and black dial — the Lady-Datejust 178240 takes the most pared-back approach possible within the collection. There is no gold, no fluting, no gemstones; just clean stainless steel architecture with a dark dial that maximises contrast and legibility. At 31mm, it is the mid-size option for buyers who want a Datejust with a sportier personality and the versatility of a monochrome steel watch.
Key Specifications
| Specification | Detail |
|---|---|
| Reference | 178240 |
| Case Size | 31mm |
| Case Material | Oystersteel |
| Bezel | Smooth domed, Oystersteel |
| Dial | Black |
| Crystal | Sapphire with Cyclops lens |
| Movement | Automatic with date |
| Water Resistance | 30m |
| Bracelet | Oyster, three-piece links |
| Clasp | Folding Oysterclasp |
| Functions | Hours, minutes, seconds, date |
The 178240 Black Dial Up Close
The black dial absorbs ambient light, creating maximum contrast against the applied stick markers and luminescent hands. This is a high-legibility configuration: white luminescent fill on the indices and hands stands out sharply against the dark surface, and the Cyclops-magnified date at three o’clock is readable at a glance. No sunburst effect here — the finish is a clean, flat black.
The smooth steel bezel reinforces the utilitarian aesthetic, sitting flush and unadorned above the dark dial. The Oyster bracelet in full Oystersteel completes a cohesive monochrome look from case to clasp. See all steel Lady-Datejust options in the Lady-Datejust collection.
Movement Options: Swiss vs Japanese
Choose from two automatic movement tiers:
- Swiss automatic — smooth high-beat sweep, extended power reserve, and architecture following the genuine Lady-Datejust caliber. Best for collectors prioritising mechanical refinement.
- Japanese automatic — reliable Miyota-based caliber with globally accessible servicing and proven daily accuracy. A practical choice for everyday wear.
Both feature quickset date and hacking seconds for precise synchronisation.








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