Short answer
The replica Audemars Piguet Perpetual Calendar 3399 is a 41mm Royal Oak style build that copies the full calendar dial: a week-of-year track around the outer edge, month and leap-year at 12 o'clock, date at 3, day at 9, and a moonphase at 6. Three things decide whether a given piece is worth buying: case thickness, dial printing quality, and the movement that actually sits inside. Check those first, because no amount of polished bracelet work fixes a thick case or a calendar that does not track.
What the 3399 label refers to
3399 is a seller-side build code, not an Audemars Piguet reference. Genuine perpetual calendar Royal Oaks carry references like 26574, 25820, and 25654. When a listing uses 3399, it is naming a specific replica configuration, usually defined by case size, dial color, movement, and factory. Ask the seller to confirm all four in writing before you compare prices, because the same code gets reused across suppliers with different parts.
Prerequisites
- A loupe, or a phone with macro mode.
- Calipers, if you want to verify thickness yourself.
- A written description of the movement and factory from the seller.
- A stated return window.
How to inspect one, step by step
- Ask for the measured case width and thickness. The original is 41mm wide and roughly 9.5mm thick; most replicas land between 10.5mm and 12mm.
- Check the week track. Move the corrector and watch whether the week hand advances one position or drifts between markers.
- Compare the month and leap-year subdial at 12 with the day at 9. Fonts should be thin, even, and black on a stepped dial.
- Look at the date at 3 under magnification. The window edge should be crisp, with no white plastic visible around the numeral.
- Examine the dial texture. Grand tapisserie squares should have depth and a matte finish, not a flat printed gloss.
- Inspect the moonphase at 6. The disc should sit level, with stars printed cleanly and not clipped.
- Turn the watch over and check the rotor engraving and caseback text. Shallow, off-center, or uneven lettering is a tell.
- Run a finger along the bracelet edges and case flanks. Sharp edges and mismatched brushing show up fast in daylight.
- Ask which movement base is inside and how the calendar module is driven. Miyota 9015 bases and Chinese automatics with an added module are common; a cloned 5134 layout is the exception.
- Confirm the return terms before you pay. A functional calendar is hard to verify from photos alone.
Movement reality check
Most of these builds stack a calendar module on top of a thin automatic base. That is why the case sits taller than the original and why the correctors feel stiff. A true perpetual calendar that accounts for leap years at the movement level is rare in this price range; many replicas show the full layout but need manual correction after short months. Ask directly whether the calendar is truly perpetual or only decorative, and get the answer in writing.
Common flaws
- Week hand that jumps two positions or stops short of a marker.
- Misaligned subdial hands after a date change.
- Casebacks with wrong reference numbers or wrong screw positions.
- Bracelet links that rattle or pinch at the clasp.
- Hands with rough edges or uneven lume fill.
Legal and disclosure note
A replica is not an Audemars Piguet watch, and selling one as genuine is fraud in the United States and most other markets. Buy it as what it is, and never pair it with genuine papers or a genuine serial.