Short answer
IW371776 is an IWC reference number. IWC made that watch. A listing that sells an "IW371776 replica" sells a copy that carries a real reference number, and the number is the cheapest part to copy. Compare the watch in hand with IWC's own photos and specs for IW371776, not with the title of the listing.
Understanding the Difference Between a Replica IW371776 Watch and a Counterfeit
The reference falls in the IWC Portugieser Chronograph range. Confirm the exact case size, dial variant and calibre on IWC's product page for that number before you compare anything.
What the reference number proves
A reference number identifies a case, a dial variant and a movement combination in a maker's catalog. It does not identify a factory. Sellers print the same number on a $90 quartz watch and on a $700 clone with a modified Asian chronograph movement. Ask for the movement type, the case diameter measured with calipers, and caseback photos before you pay.
How to Spot an IW371776 Fake Replica: A Comprehensive Buying Guide
Checks that separate a good copy from a bad one
- Case thickness. Measure with calipers. Compare the result with the figure IWC publishes for the reference. Copies run thick by 0.3 mm to 1 mm.
- Dial print. Look at the brand mark, the "Schaffhausen" line and numeral edges at 10x magnification. Copy dials show wide ink edges and uneven letter spacing.
- Subdial spacing and hand length. Hands that stop short of the track, or overlap it, point to a dial and movement that were not designed together.
- Caseback engraving. Reference and serial numbers are laser-engraved on genuine pieces. Copies show shallow, wide cuts and the wrong font weight.
- Movement. Match rotor engraving, jewel count and bridge finishing against photos of the genuine calibre. A sapphire caseback makes this a five-minute check.
- Crown. Check logo depth, thread pitch and gasket seat.
- Strap and clasp. Count stitches per inch, check edge paint on the leather, check stamp depth on the clasp.
- Weight. Weigh the head on a kitchen scale. A light head means a plated base metal case or a thin movement ring.
Paperwork is not proof
Boxes, warranty cards and booklets come from the same shops that print the watches. A card with a stamped date proves nothing on its own. Ask for the original invoice and the name of the dealer who sold the watch. Then call the dealer.
Price is the stronger signal
Steel Portugieser Chronograph models trade on the secondary market between roughly $5,000 and $9,000 USD, depending on reference and condition. An offer far below that band needs an explanation that survives a phone call. So does a "new old stock" claim on a reference that left production years ago.
Legal note for US buyers
A watch that carries another company's trademark without authorization is a counterfeit good. US Customs and Border Protection can seize such watches at import, and the seller can face a civil claim from the brand owner. Buying a replica for private use is one risk. Reselling it is a larger one.