Short answer
The IW371491 is a stainless steel IWC Portugieser Chronograph. Judge a replica of it on four points: case size, dial layout, movement type, and case finishing. Ask the seller for caliper photos across the case and a clear photo of the movement before you pay. If either is missing, walk away.
What the reference is
The Portugieser Chronograph IW371491 uses a round steel case of about 40.9 mm across and 12.3 mm thick, with 20 mm lugs, a slim bezel, and a domed sapphire crystal. The dial carries two subdials: elapsed minutes at 12 o'clock and running seconds at 6 o'clock. There is no elapsed hours counter and no date window. The calibre 79350 is a reworked Valjoux 7750 with a 44 hour power reserve and a 28,800 vph beat rate. Water resistance is rated at 3 bar, which means splash resistance only. Confirm the dial colour and hand finish against reference photos before you compare anything else, because this reference exists in more than one dial variant.
What to prepare
- Reference photos of the genuine watch from at least two angles.
- A caliper, or seller photos with a ruler laid flat across the case.
- A macro photo of the movement with the caseback removed.
- A payment method with a chargeback route.
How to check a replica IW371491
- Measure the case diameter across the bezel at 3 and 9 o'clock and confirm 40.8 to 41.0 mm.
- Measure thickness from the caseback to the top of the crystal and confirm 12.0 to 12.5 mm.
- Measure the lug gap and confirm 20 mm, then check the strap tapers to about 18 mm at the buckle.
- Count the subdials. Two only. Reject any example with a third counter or a date aperture.
- Start the chronograph, let it run one minute, then reset it. Both hands should snap to zero in one motion.
- Read the dial printing at 2x magnification. Look for uneven numeral spacing and a minute track that drifts off centre near the date position.
- Turn the crystal under a desk lamp and check for the blue or purple tint of an antireflective coating on both faces.
- Request a movement photo and match the rotor engraving font and balance cock shape against reference images.
- Inspect the brushed flank and the polished bezel edge under raking light. The grain should run one direction and stop at a crisp line.
- Check clasp engraving depth and how the strap ends sit against the case. Gaps here show up on the wrist.
Movement choices you will meet
Three movements turn up in copies of this reference: an Asian 7750 clone, a Seagull ST19 hand wound chronograph, and on rarer builds a Swiss 7750. The clone gives automatic winding, instant reset, and a reserve near 40 hours. The ST19 feels smoother at the pushers but needs daily winding and has no rotor, so a caseback photo will show the difference at once. Ask which movement is fitted and price the watch against that answer. A seller who calls a hand wound movement automatic is either careless or misleading, and both matter at this price.
Red flags
- Photos that hide the caseback or crop the movement.
- A case that measures 42 mm or more, which is a different watch family.
- Pushers that click instead of travel with resistance.
- Dial text that sits too low or too high against the centre line.
- Any claim of factory-direct stock with no serial photo.
Legal and import reality
Counterfeit goods that carry a registered trademark are illegal to import into the United States and the European Union. Customs officers can seize and destroy a shipment, and you carry the loss. Marketing phrases about customs-safe delivery do not change the rule or shift the risk away from the buyer. Read the seller's terms on seizure and refunds before you order, and treat a vague answer as a no.
After delivery
Inspect the watch within 48 hours of arrival. Wind it fully, leave it dial up for a day, and note the timekeeping. Run the chronograph through ten start, stop, and reset cycles. Keep the watch away from water regardless of the caseback rating, since gaskets on copies are not tested to the same standard. Have the movement serviced every three to four years if you wear it often.