Short answer
A replica Audemars Piguet 16402 parts company with the genuine watch at five points you can check without opening the case back: bezel screw geometry, tapisserie dial surface, bracelet link taper, case flank bevels, and clasp engraving. Movement decoration is the sixth. Score those six items and the build quality sorts itself out.
Before you compare
- Reference photos of the genuine 16402 from the brand's product page or an auction archive
- A 10x loupe
- Digital calipers
- A gram scale accurate to 0.1 g
- Even light from a window or a desk lamp with a diffuser
- A timegrapher or a phone app that reads rate and beat error
Comparison procedure
- Weigh the watch head and the full bracelet on the gram scale and write both numbers down.
- Measure case width, case thickness, and lug-to-lug span with the calipers and record each figure against the published specification.
- Count the eight bezel screws and check that each head sits flush in its recess.
- Study screw slot orientation: on the genuine, the slots follow a consistent line around the octagon, and replicas often leave one or two rotated.
- Angle the dial toward the light and examine the tapisserie squares for edge sharpness, matte tops, and even spacing across the whole dial.
- Check the date aperture for font weight, print clarity, and centering inside the window.
- Inspect the hands: polished bevels along the top edge, clean tips, and length that reaches the printed minute track.
- Run a fingertip along both bracelet edges to feel for chamfered links and a smooth taper from the case to the clasp.
- Open the clasp and compare the engraved brand mark for depth, sharp corners, and crisp letterforms.
- Turn the watch over and compare the case back engraving of reference and serial numbers, then inspect the movement for stripe finishing, polished screw heads, and a skeletonized rotor with clean cutouts.
- Set the watch against a reference clock and read the rate and beat error after 24 hours.
How to score what you find
- Minor: a half-millimeter size difference, faint engraving, or a rate inside plus or minus five seconds per day.
- Moderate: screw slots out of line, shallow dial squares, or a bracelet that does not taper.
- Major: proud screws, printed dial texture, mismatched signature, or a rotor with tool marks.
What the comparison cannot tell you
Case finish and dial texture are visible. Water resistance, shock protection, and long-term parts support are not. A replica has no factory service channel, no warranty on the movement, and resale value that drops the moment you buy it. Treat any water resistance claim as untested, and keep the watch away from pools and showers. Use the comparison to judge craftsmanship, not to assume the replica behaves like a genuine 16402 in daily wear.