Quick answer
A fake IW371747 is a replica of an IWC Portugieser chronograph. The 3717xx block of IWC reference numbers sits inside the Portugieser line. Published specs for the exact number IW371747 are thin, so ask the seller for a dial photo and the case diameter, then compare both against IWC's own record for that reference before you judge any replica against it.
Replica stock comes in three price bands. Quartz copies run $70 to $120. Copies with an Asian chronograph movement run $250 to $450. Copies with a modified Swiss-clone movement run $600 and up. The price gap shows up in case thickness, subdial spacing, engraving depth and movement finish, not in the dial print.
Checks on the watch itself
- Case thickness. Measure with calipers. Cheap copies add 1 mm to 2 mm against the reference.
- Subdial spacing. The two counters should sit on the same horizontal line as the crown. Bent or raised spacing means a stock movement was forced into the case.
- Date window. Check the font, the frame edge and the cut. Thin frames and wrong numerals are common on the $250 band.
- Caseback engraving. Run a fingernail across it. Laser etch sits flat. Engraved text has depth and a burr line.
- Chronograph pushers. Start, stop and reset the timer 20 times. A grinding feel or a hand that fails to snap back points to a low-grade module.
- Weight. Weigh the watch without the strap. Record the number and compare it to another copy from the same batch.
- Strap. Check stitch count per inch and the buckle tang thickness. Most copies ship with corrected-grain leather, not calf.
Papers, box and service
A replica arrives with a printed card and a generic box. Neither carries a serial that resolves in IWC's service system. IWC will not service a counterfeit, and no authorized repair center stocks parts for one. Ask about water resistance in writing. Sellers list 30 m or 50 m on paper, but most copies leave the factory without a pressure test.
Legal and shipping facts in the US
19 U.S.C. § 1526 bars import of goods that carry a counterfeit mark. US Customs and Border Protection can seize a parcel and send a notice to the buyer. Seizure risk rises on multi-unit orders. Resale of a counterfeit watch as genuine is a separate offense under trademark law. Keep the order to one unit if you accept the risk.
What the copy does not include
No warranty from IWC, no service history, no tested water resistance, no resale value. Budget for a movement service at $120 to $200 within two years on the mechanical tiers. A quartz copy needs only a $10 battery, but the case finish will not hold up past a year of daily wear.