This replica nautilus 57121A black delivers the 5712/1A-001 reference in a 40mm stainless steel case with a black dial carrying three subdials: moon phase, power reserve, and date. Where the 5711 keeps the dial minimal, the 5712 fills the same 40mm case with practical complications that add daily functionality. Patek Philippe fitted this reference with the ultra-thin caliber 240 PS IRM C LU, one of the slimmest automatic movements capable of driving a moon phase display alongside a power reserve indicator and pointer date.

Technical Details

• Case diameter: 40mm
• Case material: stainless steel
• Dial: black with three subdials
• Subdial at ten: moon phase
• Subdial at seven: power reserve
• Subdial at center-bottom: pointer date
• Bezel: polished octagonal
• Bracelet: integrated stainless steel
• Movement: automatic

The moon phase indicator at ten o’clock uses a disc with two painted moons that cycle through the full 29.5-day lunar period. The power reserve at seven shows remaining energy in the mainspring.

Movement Analysis

The caliber inside the 5712 uses a micro-rotor design instead of a full-size rotor, which allows the movement to remain thin enough for the Nautilus case profile. This design choice separates the 5712 from most complication watches that sacrifice case thickness for functionality. The black dial grounds the three subdials visually, preventing the face from feeling cluttered despite the additional displays. Explore the broader Nautilus collection to see how simpler and more complex references compare at 40mm. For a radically different Nautilus format, see the 7118/1200R ladies automatic in diamond brown.

What Sets It Apart

The 5712 answers a specific question: what happens when you add real complications to the Nautilus without changing the case size. The answer is a watch that wears identically to the 5711 on the wrist but delivers moon phase tracking, power reserve monitoring, and pointer date in one glance. Black on stainless steel keeps the aesthetic grounded. This replica nautilus 57121A black occupies the sweet spot between the simplicity of the 5711 and the full calendar complexity of the 5726.