A fake IW371436 succeeds or fails on three measurements: case thickness, sub-dial spacing, and the movement under the dial. Match those and the watch reads as an IWC Portugieser Chronograph on the wrist. Miss them and no amount of caseback engraving saves it. Strap stitching and box printing are detail work you grade after the basics pass.

What the IW371436 actually is

Reference IW371436 sits in the IWC Portugieser Chronograph family: a stainless steel chronograph around 40.9 mm across, with a clean dial, applied Arabic numerals, leaf hands, and two sub-dials positioned at 12 and 6. Water resistance is rated to 3 bar, and the caseback is closed. A replica of this reference has to reproduce that layout before anything else matters.

Check the case before the dial

Ask for the case dimensions in writing. Diameter should land near 40.9 mm, thickness near 12.3 mm, and lug width at 20 mm. Thin cases are the most common shortcut: a 10 mm watch will not sit like a Portugieser, no matter how good the dial looks.

Look at the side profile next. The bezel is polished, the case flanks carry a brushed finish, and the lugs curve down with a distinct step where they meet the case. Pushers should be round, sit at 2 and 4, and travel with a firm click. A mushy pusher usually signals a cheap chronograph module.

Dial details that separate grades

The sub-dials are the tell. On the reference they sit close to the vertical center line with tight, even spacing from the hour track. Fakes with wide gaps or sub-dials pushed toward the edge are using a stock layout, not a copy of this dial.

Print quality comes next. The "IWC Schaffhausen" signature and the text above 6 should be sharp under a loupe, with no bridging between letters. Numerals are applied and polished, not printed. Sub-dial hands should reach their minute tracks. There is no date window at 3, so any fake showing one is copying the wrong reference.

Movement: the biggest fork

The 3714-generation case runs the 79350 calibre, a chronograph built on a Valjoux 7750 base. Replicas usually carry one of three movements: a basic Chinese 7750 clone, a decorated Asian automatic with a false rotor, or a modified 7750 finished to resemble the original. Ask which one is installed and request a clear photo of the movement with the caseback off.

Then test function. Start the chronograph, let it run two minutes, and reset. The sweep hand must return to zero in one motion. Running seconds at 6 should move in small steps, not a smooth glide.

Caseback and hardware

Engraving on the caseback should be laser-sharp with even depth, and the reference number must match IW371436 exactly. Check the crown: it should be signed, sit flush, and wind without grit. The strap or bracelet matters less, but the buckle should be signed and the spring bars should be the correct thickness for the lugs.

Nine-point inspection routine

  1. Measure the case diameter, thickness, and lug width with calipers.
  2. Confirm sub-dial spacing against a photo of the genuine reference.
  3. Inspect dial printing with a 10x loupe.
  4. Verify the numerals are applied and polished, not painted.
  5. Start and reset the chronograph three times.
  6. Check that the sweep hand returns to zero without drift.
  7. Wind the crown fully and note any grinding.
  8. Read the caseback engraving and confirm the reference number.
  9. Weigh the watch and compare against the listed figure.

Questions to ask before paying

  • Which movement is inside, and can you send a photo of it?
  • What are the exact case dimensions?
  • Can you send a video with a timestamp showing the chronograph running?
  • Is the watch in stock, or is this a stock photo?
  • What is the return policy if the watch arrives off-spec?

Red flags

  • Catalog photos only, with no live shots.
  • Claims of "1:1" or "identical to genuine" with no measurements supplied.
  • No movement photo and no answer when you ask.
  • Prices far below the going rate for the grade described.

Set realistic expectations

Even the best fake IW371436 will not match the finishing or serviceability of a 79350 movement, and resale value is zero. Treat the purchase as a look-alike, price it that way, and keep in mind that selling counterfeit goods carrying a trademark is illegal in the United States. Buy to wear, not to pass off as genuine.