Short answer

A fake Audemars Piguet ref. 15500 nearly always fails in the same five places: the tapisserie pattern on the dial, the date window and its font, the bezel screws, the fit between the bracelet and the case, and the finishing visible through the display back. A genuine ref. 15500ST uses a 41 mm case with Calibre 4302 and a 70-hour power reserve, so any watch advertised as a 15500 with a different movement layout is wrong before you look any further.

Prerequisites

  • A 10x loupe or a phone macro lens
  • Bright, diffused light and a dark background
  • A catalog photo of a genuine ref. 15500ST for side-by-side comparison
  • Calipers if you want to verify case and bracelet dimensions
  • Access to a watchmaker who can open the case back

Check the dial first

  1. Hold the watch at a shallow angle and look across the tapisserie grid. Genuine dials are cut from one piece, so the tops of the squares reflect light in an even, repeating pattern. Copies often show squares with soft edges or a slightly different depth.
  2. Follow the gap between the dial edge and the inner bezel ring. It should stay the same width the whole way around. A wavy or pinched gap points to a copied dial sitting in a copied case.
  3. Read the printed signature with the loupe. "Audemars Piguet" and "Automatic" should have clean, sharp edges on every letter. Thick, fuzzy, or uneven lettering is a strong sign of a fake.
  4. Compare the position of the printed text to your reference photo. On fakes the signature often sits slightly high or low because the dial was copied from a photograph.

Inspect the date window

  1. Look at the shape of the aperture. Genuine 15500 date windows have a polished, angled frame; fakes usually have a flat cut with a visible burr.
  2. Compare the date font to a known photo. The numerals should be thin, upright, and evenly spaced. Copy dials often use a wider, heavier font.
  3. Cycle the date through several days. Each numeral should sit centered in the window at the same height. Drifting or tilted numerals mean the date disc and the dial do not match.

Examine the bezel and screws

  1. Count the hexagonal screws. A ref. 15500 has eight, and each should sit flush with the bezel surface. Screws that stand proud of the bezel or sit in a recessed well are wrong.
  2. Check the socket edges with the loupe. Genuine screws have crisp, straight hexagon walls. Fakes show rounded corners or tool marks from a poorly cut die.
  3. Do not treat screw slot alignment as proof either way. Alignment varies on genuine watches after service, so use it only as a supporting signal.

Test the bracelet and clasp

  1. Flex the bracelet and feel the links move. Genuine links pivot smoothly with almost no side play. Copies rattle and show gaps between links.
  2. Look at the joint where the end links meet the case. The fit should be tight and even on both sides, with no step or shadow line.
  3. Close the clasp and check the engraving and folding action. Genuine clasps snap shut with a firm click and carry deep, sharp stamps. Shallow laser etching is common on fakes.

Study the case back and movement

  1. Read the reference and case numbers with the loupe. On a genuine watch the engraving is cut into the metal with sharp edges and consistent depth. Printed or shallow etched numbers are a red flag.
  2. Compare the reference number to the full AP reference for that model, including the bracelet code.
  3. Look through the sapphire back at the movement. Calibre 4302 shows striped bridges, polished bevels, and a decorated oscillating weight. Copy movements show flat plates, rough edges, and painted or glued decoration.
  4. Have a watchmaker open the case if the seller allows it. The movement number, rotor construction, and finishing under the rotor settle the question.

Confirm the paperwork and serials

  1. Match the case number on the back to the number on the warranty card and any service papers. Mismatched numbers mean the set was assembled from parts.
  2. Book an inspection at an authorized Audemars Piguet service center. Staff there can confirm the reference against brand records, and they will refuse to service a counterfeit.
  3. Walk away from any deal that requires payment before an inspection. Legitimate sellers allow a pre-purchase check.

What a visual check cannot tell you

High-end copies now use correct case dimensions and copied dial artwork, so a photo comparison alone is no longer enough. Weight helps, but steel copies can be weighted to match. The reliable tests are the movement, the case back engraving, and the serial records held by the brand. Treat every other signal as supporting evidence only.