Quick answer
Most fake IW323743 watches fail at the caseback. Genuine IWC engraving cuts into the metal with sharp edges, the reference number follows the model family and variant logic, and the serial number on the caseback matches the serial stamped on the movement. Replicas use shallow stamping, wrong fonts, and numbers that do not agree with each other. Work in this order: caseback, serial match, movement, dial print, date window, crown, bracelet, then timing. Two or more failures means the watch is not genuine, no matter how good the photos look.
Before you start
- A 10x loupe or a phone macro lens
- A bright light you can angle across metal
- A reference photo of a known genuine IW323743 caseback and dial
- A caseback opener, if the seller allows the back to come off
- A timegrapher or a watch timing app
Inspection steps
- Read the caseback engraving and confirm the digits spell IW323743 with nothing added and nothing missing.
- Angle the light across the engraving and confirm the letters are cut into the metal rather than stamped on the surface.
- Compare the font to your reference photo, watching the shape of the numeral 1 and the spacing between 3 and 7.
- Locate the serial number and match it digit for digit to the serial on the movement rotor or bridge.
- Remove the caseback and look for an IWC caliber marking; a blank plate or a generic movement stamp ends the inspection.
- Study the dial under the loupe and check that applied markers sit level and lume fill stops inside each frame.
- Check the date aperture for a beveled edge and a date font with the same stroke weight as the dial print.
- Turn the crown through a full screw-down cycle and note any grit, wobble, or loose thread engagement.
- Handle the bracelet and press each end link against the case; there should be no side play and no gap.
- Run the watch on a timegrapher and record the beat rate, since most IWC automatics beat at 28,800 vph and a 21,600 vph reading points to a substitute movement.
Where replicas give themselves away
- Caseback text that sits too deep, too shallow, or filled with paint
- Serial numbers that repeat across different watches, a sign of batch production
- Movement rings with rough machining marks and no decorative finish
- Dial print that sits on top of the lacquer instead of under it
- Bracelet screws with soft heads that burr on the first turn
- Boxes and papers printed on stock card with the wrong reference on the warranty page
If you cannot open the watch
Ask the seller for a photo of the movement with the caseback removed, a photo of the warranty card showing the full reference and serial, and the original purchase receipt. Genuine sellers supply all three without argument. A seller who refuses, or who sends photos lifted from a dealer site, has already answered your question.