Short answer
IW371491 sits in the IWC Portugieser Chronograph line. The 3714 block of reference numbers covers several dial variants of that model, so match the full number and not the first four digits. Before you pay, confirm the number in IWC's own catalog or in a service record. Counterfeit versions exist, and most of them fail three checks: subdial spacing, movement finish, and caseback engraving.
What the real watch measures
- Case: stainless steel, round, polished bezel, 41 mm across, 13.1 mm thick on the current reference.
- Movement: calibre 69355, automatic, 4 Hz, 46 hours of power reserve, 27 jewels. Earlier 3714 references used a Valjoux 7750 base.
- Crystal: sapphire on the front, sapphire caseback on most versions.
- Dial: two subdials, chronograph minutes at 12 and small seconds at 6, applied numerals, feuille hands.
- Strap: alligator leather on a steel pin buckle or folding clasp.
Checks that catch most fakes
Caseback engraving
Read the reference number, the serial number, and the material code. Genuine IWC engraving has sharp edges and even depth. Copies show shallow, rounded letters and uneven spacing. The reference on the caseback must match the reference on the paperwork.
Movement
Open the caseback or study the seller's movement photo. A real 69355 has Geneva stripes on the bridges, perlage on the base plate, blued screws, and the IWC wordmark on the rotor. A 7750 clone shows a rotor with a printed logo and no bevel on the bridge edges. No replica carries a genuine IWC movement. A listing that says otherwise is false.
Subdials and hands
Compare subdial centers against official photos taken at the same angle. Copies shift the subdials by a millimetre or two because the movement underneath is a different shape. Feuille hands on the genuine watch have a polished bevel along the full length. Copies show a flat, painted surface.
Crown, pushers, and weight
The crown on the genuine watch winds with light resistance and no grit. Pushers start and reset the chronograph with a short, firm travel. Copies feel loose. A steel case of these dimensions weighs more than a plated brass case of the same size. A kitchen scale shows the gap.
Strap and clasp
IWC alligator straps have even stitching and a stamped inner lining. Buckles carry the logo and the steel grade. Copies use embossed calf leather and a cast buckle.
Price and paperwork
US retail for a steel Portugieser Chronograph sits near $8,000. Used pieces sell below that. A price far below the market band points to a copy or to a stolen watch. Ask for the invoice, the warranty card, and the service book. Match the serial number to the card. A missing serial or a re-stamped caseback is a stop sign.
Replica grades
Sellers sort copies by tier. An entry tier uses a 7750 clone with a printed rotor and a case that is 1 mm to 2 mm off. A mid tier adds a sapphire crystal and closer dial printing. A top tier copies the case dimensions and the dial, and still uses a third-party movement. Case dimensions can match. The movement can not, and the movement decides service life and long-term rate.
Six steps before you pay
- Search the full reference number, not the first four digits.
- Request photos of the dial, the caseback, and the movement.
- Compare those photos with official images at the same angle.
- Check the serial number with an IWC boutique or service centre.
- Weigh the watch and test the crown and pushers in person if you can.
- Use a payment method that lets you open a claim.