Short answer

A fake IW3717 is a copy of the IWC Portugieser Chronograph reference family IW3717xx. The genuine watch has a 40.9 mm steel case, a 30 minute counter at 12, small seconds at 6, and a date at 3. Replicas come in three grades. Most fail on subdial spacing, date print, case thickness, and movement finish.

Reference specs

  • Case: 40.9 mm diameter, 12.3 mm thick, stainless steel
  • Movement: calibre 79350, 44 hour power reserve, Valjoux 7750 base
  • Subdials: small seconds at 6, 30 minute total at 12
  • Date: aperture at 3
  • Crystal: domed sapphire, antireflective coating
  • Water resistance: 30 m
  • Caseback: screw down, engraved reference and serial

Where replicas fail

  1. Subdial spacing. Measure center to center on both subdials. Copies drift by a millimeter or more.
  2. Case thickness. The reference runs 12.3 mm. Many copies run 13 to 14 mm and sit high on the wrist.
  3. Hand length. The leaf hands on the reference reach the minute track. Copies run short and stop before the printed track.
  4. Dial print. Check the stroke weight on the brand text and the word Automatic. Copies print thick.
  5. Date window. Check the font, the size of the cut, and the position against the index at 3.
  6. Crystal. Look at the edge height and the coating tint. A blue cast under light is a common tell.
  7. Pushers and crown. Check the shape, the finish, and the crown engraving.
  8. Caseback. Check engraving depth, the reference number, and the serial. A serial that repeats across listings is a sign of a stock photo.
  9. Movement. Look at rotor engraving, bridges, and perlage. A clone of the 7750 shows a plain finish.

Price tiers

Low grade copies use a quartz movement or a basic automatic and skip the case profile. Mid grade copies use a clone of the 7750 and get the dial layout close. Top grade copies work on case thickness, dial print, and hand length, but the movement stays a clone and the finish stays visible through the caseback.

Before you buy

  1. Ask for a macro photo of the date window and the subdial hands.
  2. Ask for the measured case thickness with calipers.
  3. Ask for a photo of the caseback with the serial visible.
  4. Ask for a video of the chronograph start, stop, and reset.
  5. Get the return window in writing.

Limits of photo checks

Photos do not settle authenticity. A watchmaker with the watch in hand can check the movement finish, the caseback threads, and the crystal. No photo set from a seller replaces that. Sale of counterfeit branded watches is illegal in the US and the EU, and buyers in those markets carry the risk.