Quick answer

Reference 16402 is an Audemars Piguet Royal Oak case number. Fakes built on this number appear at swap meets, online auctions, and gray-market listings. The tells sit in the bezel screws, the dial texture, the caseback engraving, and the movement. A photo check catches most of them. A watchmaker with the caseback off catches the rest.

What reference 16402 is

The 16402 number sits in the Audemars Piguet Royal Oak range. AP does not publish a full production list for the reference. Build years, dial codes, and metal combinations come from the AP archives in Le Brassus, not from a public sheet.

That gap is what fakes exploit. A seller can claim any date or dial code, and a buyer has nothing public to check against.

Case and bezel

  • Bezel screws: the Royal Oak has eight hexagonal screws. On genuine cases the slots line up close to radial. On fakes the slot angles are random.
  • Fake screw heads sit proud of the bezel or sit too deep. Genuine heads sit flush.
  • Case thickness runs high on fakes. The bezel and mid-case look chunky next to a real one.
  • Bezel facets: the beveled top edge should be a crisp line. Fakes show rounded or uneven edges from casting.
  • Crown: signed AP. Fakes use a plain crown or a weak stamp.

Dial and hands

The dial on a Royal Oak of this era uses a stamped tapisserie grid. Lines are sharp. Squares are cut, not printed.

  • Fakes print the grid. Look at the dial at an angle. A printed grid goes flat under light.
  • Text quality: "Audemars Piguet" and "Automatic" should be clean at 10x. Fake text shows broken serifs and uneven spacing.
  • Date window: the cut is square with sharp corners. Fake windows are oval or off-center.
  • Hands: polished, with a flat top facet. Fake hands show tool marks.

Movement and caseback

The genuine watch uses an Audemars Piguet calibre. Fakes use a modified ETA or a Chinese automatic with an engraved rotor. A rotor engraving proves nothing. Movement finish, jewel count, and regulator layout are what a watchmaker reads.

Caseback engraving covers the reference number, serial number, and metal marks. Fonts on fakes are wrong in weight and spacing. Serial ranges for the period vary. Confirm any number with Audemars Piguet before payment.

Bracelet and clasp

  • Links taper. The last link at the clasp is narrow.
  • End links sit flush with the case. Gaps at the lugs point to a fake.
  • The clasp logo is stamped deep and even. Fake stamps are shallow.
  • Bracelet screws take a flat blade. Fake screws strip.

Papers, price, and legal notes

Boxes, booklets, and archive extracts get faked too. Buy from a seller who allows a watchmaker inspection and a return. Auction results from Phillips, Sotheby's, and Christie's give real price points for the reference.

Counterfeit watches are illegal to sell as genuine in the US and the EU. Customs agencies seize them.

Limits of a photo check

Photos hide thickness and movement. Ask for a caseback shot, a movement shot, and a side profile. If the seller refuses, stop.