Short answer
IW371756 appears in listing titles for replica IWC Portugieser chronographs. IWC's public catalog does not show a reference with that number. IWC case numbers use the format IW plus six digits, and current Portugieser Chronograph references sit in the IW3716xx range, such as IW371617. If a seller writes "IW371756," treat the number as a listing label, not a factory reference.
What the genuine watch is
The IWC Portugieser Chronograph is a 41 mm steel watch with two subdials, a printed minute track, and a leaf-shaped handset. The current generation runs the IWC calibre 69355, an automatic column-wheel chronograph with a power reserve near 46 hours and a beat rate of 28,800 vph. It uses a sapphire crystal, a sapphire display back, and a screw-in crown. Retail pricing sits in the high four figures in US dollars and moves with strap and case metal.
Why the number shows up in searches
Replica listings generate their own reference strings. Sellers mix real prefixes with invented digits to dodge takedown notices and to make each listing look new. A search for "fake iw371756" lands on aggregator pages, not on an official spec sheet. No IWC parts list or service document carries that number.
Points that separate a replica from a genuine Portugieser
- Subdial spacing. Genuine 41 mm models place chronograph minutes at 12 and running seconds at 6. Many replicas shift these positions or use a different subdial diameter.
- Movement. Genuine watches use calibre 69355 with a column wheel and set finish. Replicas often use an Asian 7750 derivative, a Seagull ST19, or a quartz module. Rotor engraving and jewel count differ.
- Date window. On date models the aperture sits at 3 o'clock with a matched numeral font. Replicas show a wider window or a different numeral shape.
- Caseback text. Depth of the reference, serial, and model engraving varies. Genuine engraving is crisp and shallow.
- Dial printing. "IWC" and "SCHAFFHAUSEN" are thin and sharp on genuine dials. Replicas show thicker strokes and uneven letter spacing.
- Crown. The fish logo is stamped on the crown of many IWC models. Replicas show a soft outline or no logo.
- Weight and finish. Brushed and polished transitions are sharp on genuine cases. Replica cases show rounded edges and lower weight.
- Papers. Genuine watches ship with a warranty card, a matching serial, and a booklet. Replicas ship with a generic card and no dealer stamp.
Replica grade labels
Listings use terms such as AAA, mirror quality, 1:1, and Swiss movement. None are regulated. "Swiss movement" in a replica listing often means an Asian movement with a Swiss-labeled rotor. "1:1" describes similarity in photos, not in hand. Price bands for these watches run from about $80 to $900. Claims above that range come from the seller, not from a factory standard.
US legal position
Importing a counterfeit watch into the United States is prohibited. 19 U.S.C. 1526 lets US Customs and Border Protection seize and destroy counterfeit goods, and 18 U.S.C. 2320 makes trafficking in counterfeit goods a criminal offense. One watch can be seized. Resale adds exposure under the Lanham Act. IWC records its trademarks with CBP, so shipments are screened.
What to check on any listing
- Verify the reference against IWC's catalog.
- Ask for a photo of the caseback and the movement.
- Compare subdial positions with a genuine photo from IWC.
- Ask for the serial and match it to the warranty card.
- Assume no return right on cross-border shipments.