A fake IW371748 is a watch sold as the IWC Portugieser Chronograph reference IW371748 but not built by IWC. You catch one by pulling the official specs for that reference, then comparing case dimensions, dial printing, chronograph action, and caseback engraving against a verified genuine example before money changes hands.
What to have on hand
- The published spec sheet for the reference: case size, caliber, dial variant, strap.
- A 10x loupe.
- Digital calipers or a steel ruler.
- Bright, diffused light.
- Photos of a known genuine IW371748, shot from the front, back, and side.
- Seller paperwork: warranty card, receipt, box, and serial number.
How to check an IW371748 step by step
- Read the caseback. The reference, case number, and caliber should be engraved in one clean, even line. Compare the numbering format against IWC records, not against a listing photo.
- Measure the case across the bezel and from lug tip to caseback. Counterfeit cases land half a millimeter to a full millimeter off spec, and the lugs sit thicker than the genuine profile.
- Put the loupe on the dial. Study the IWC wordmark, the Schaffhausen line, and the minute track. Genuine printing has sharp edges and even spacing. Copies show ink bleed, uneven letter height, and a font that runs heavy or thin.
- Check subdial position. The subdials should sit on the vertical axis with matched margins to the bezel. Fakes shift them a fraction and the gap between subdial and center pin reads wrong.
- Inspect the hands. Confirm length, polish, and a sweep hand that reaches the minute track. Blued steel shows deep color; paint shows flat blue.
- Run the chronograph. Start it, let it run, stop it, reset it. A column-wheel movement starts with no jump and snaps back to zero in one motion. Pushers feel crisp and short.
- Examine the crystal. Sapphire with anti-reflective coating throws a faint blue or purple sheen under light. Look for edge distortion and a flush fit to the bezel.
- Turn the watch over. On a display back, check finishing: Geneva stripes, circular graining, an engraved rotor. Copy movements show rough edges, plated parts, and generic engraving.
- Weigh it in your hand. A steel case with a solid movement carries real heft. A counterfeit feels light and hollow.
- Match the paperwork. The case number on the card must match the caseback. Ask for a service record if the seller claims one.
Details counterfeiters get wrong
Most IW371748 copies fail on small things rather than the overall shape. Look at the crown engraving, the fit of the strap to the lugs, the stitching pitch on the leather, and the lettering on the buckle. Check the dial feet from the back if the case has a display back. If the reference includes a date window, the frame cut and numeral font are common failure points. Box printing is another tell: genuine packaging uses dense, sharp print on heavy stock, while counterfeit boxes look washed out.
Price and paperwork signals
A price far below the going rate for the reference is the first red flag, and it is the one most buyers ignore. Sellers who refuse a video call, who only accept irreversible payment, or who cannot show the warranty card next to the watch are describing a counterfeit. Ask for a timestamped photo of the caseback and the card in the same frame.
Counterfeit, replica, and homage
The words matter. A counterfeit is presented as a genuine IWC and priced as one. A disclosed replica is sold openly as a copy, and an homage borrows the look without copying the name. Passing a copy off as genuine is fraud in most markets. If a seller dodges the question of origin, treat the watch as counterfeit.
Quick checklist
- Case diameter and thickness match the spec sheet.
- Dial print is sharp under 10x magnification.
- Chronograph starts smooth and resets to zero in one motion.
- Caseback engraving is crisp and the numbers match the paperwork.
- Weight feels solid, not hollow.
- Price and payment terms follow normal market practice.