The replica royal oak 15400ST blue is the one collectors actually hunt. AP discontinued the 15400 in 2019 when the 15500 took over, and since then secondary market prices on the blue dial have done nothing but climb. The reason is simple: at 9.8mm thick, this is noticeably thinner than its replacement. That millimeter makes a real difference on the wrist. The “Bleu Nuit” dial is the most requested variant by a wide margin.
The Case for the 15400 over the 15500
Numbers tell the story. The 15400 is 9.8mm thick. The 15500 that replaced it is 10.6mm. Less than a millimeter on paper, but pick up both watches and you feel it immediately. The 15400 slides under a shirt cuff without catching. The 15500 sometimes does not.
The Cal. 3120 inside runs at 21,600 vph — slower than the newer 4302 in the 15500. Some argue the lower beat rate is actually better for long-term reliability. Fewer oscillations per hour means less wear on the escapement. Sixty hours of power reserve is generous for a movement designed in the early 2000s.
AP produced the 15400 from 2012 to 2019. Seven years. Not a long run by Audemars Piguet standards. The blue dial version outsold every other color by roughly three to one according to dealer estimates. That popularity is exactly why this replica royal oak 15400ST blue remains in such high demand. The same reference on rubber strap offers a sportier alternative.
Bleu Nuit Grande Tapisserie
AP calls this shade “Bleu Nuit” — night blue. It is darker than the blue on the current 15500 or 26240. Under artificial light it can read almost black. Step outside and the blue reveals itself, especially when the tapisserie pattern catches sunlight at shallow angles. Each tiny square in the grid reflects independently.
The applied markers are white gold with luminescent fill. Date window sits at 3 o’clock with a color-matched date disc. No magnification on the crystal — AP never uses cyclops lenses. The hands are the Royal Oak standard: dauphine shape, faceted, with lume strips.
Bracelet is the classic AP integrated design with alternating brushed center links and polished outer links. The clasp is a folding butterfly with twin push-buttons. It sits flat and does not dig into the back of the wrist. Check our warranty terms for coverage details.
| Reference | 15400ST.OO.1220ST.03 |
| Case | 41mm · Stainless steel |
| Bezel | Octagonal · 8 hexagonal screws |
| Dial | Blue “Bleu Nuit” · Grande Tapisserie |
| Crystal | Sapphire · AR coating |
| Caliber | 3120 · Automatic · 60h reserve |
| Bracelet | Stainless steel · AP integrated link |
| Buckle | Steel · AP folding clasp |
| Water | 50m / 5 ATM |
| Functions | Hours, minutes, seconds, date |
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