Quick Answer
A replica IW371734 is a counterfeit copy of the IWC Portugieser Chronograph sold under reference IW371734. The genuine watch is a 40.9 mm stainless steel chronograph with two subdials, a date at 3 o'clock and an alligator strap. Good replicas copy the case diameter, dial printing and crown profile well enough to pass at arm's length. They give themselves away in the movement, the caseback engraving depth, the hand finishing and the weight. Judge a replica the same way you judge a used genuine watch: reference number first, dimensions second, movement third, finish last.
One note before the checklist. Selling, importing or shipping counterfeit watches is illegal in the United States and across the European Union. This guide explains how these products are assessed, which is useful whether you are comparing listings, writing a review or trying to spot a fake being sold as real.
Genuine Reference Points
You cannot grade a copy without a baseline. The numbers below come from the IW3717 generation of the Portugieser Chronograph, the family that reference IW371734 belongs to.
- Case: stainless steel, 40.9 mm diameter, about 12.3 mm thick.
- Movement: calibre 79350, an IWC-modified Valjoux 7750 with a 44-hour power reserve.
- Dial: chronograph minutes at 12, running small seconds at 9, date at 3.
- Crystal: domed sapphire with anti-reflective coating.
- Water resistance: 3 bar, roughly 30 m.
- Strap: Santoni alligator leather with a steel buckle or folding clasp, depending on the production year.
IWC reused dial colours and case metals across many references in this line. Vendors mix them up often. Confirm the dial colour and hands of the exact IW371734 build before you compare anything else.
Replica Tiers
Quartz tier
Thin cases, a ticking seconds hand and subdials that are often decorative. The diameter is usually wrong by half a millimetre or more, and the pushers sit too high on the case flank. These are easy to identify in person.
Asian 7750 tier
The most common serious copy. It uses a Chinese-made 7750 clone with the small seconds rerouted to 9 o'clock and the 30-minute counter at 12. Sweep is correct, pusher feel is close, power reserve lands near 40 hours. Case size is usually accurate.
Top tier with Swiss movement claims
Sellers advertise a Swiss 7750 or a modular build. Some listings are honest, some are not. Ask for a movement photo with the rotor removed before accepting that claim.
Step-by-Step Inspection
- Request the exact reference and dial variant from the seller, then compare it against photos of a genuine IW371734.
- Measure the case diameter with calipers across the bezel at 3 and 9 o'clock. Expect 40.9 mm, plus or minus 0.3 mm.
- Measure thickness from the caseback to the top of the crystal. Anything below 12 mm or above 13.5 mm points to a different case.
- Inspect dial printing under a loupe. Check the IWC wordmark, the Schaffhausen line and the text above 6 o'clock for thickness and spacing.
- Look at the subdial hands. Genuine hands are slim, blued or rhodium plated, and sit close to the dial.
- Check the date window for a clean cut with sharp inner corners, then check the date font for the correct numeral shape.
- Tilt the watch under a desk lamp and look for the blue or purple anti-reflective tint around the crystal edge.
- Run the chronograph: start, stop, reset, three times. The reset should snap to zero with no drift.
- Examine the caseback engraving depth and the serial font under a loupe. Etched text looks shallow and fuzzy next to the genuine stamping.
- Weigh the watch head on a kitchen scale. A steel case with a 7750 inside sits close to the genuine figure; a quartz case feels light.
- Check strap stitching density and the buckle stamping, since these are replaced most often.
Common Tells
- Subdials that sit too far apart or too close to the centre.
- A crown that is too small or has a soft, rounded logo.
- Case flanks that are polished where the genuine is brushed.
- Misaligned date window, most often sitting high in the aperture.
- Strap that smells of plastic or has uneven stitch spacing.
- Movement noise on the wrist from a loose rotor bearing.
Service and Longevity
A 7750-based copy can be serviced by any watchmaker who works on the platform, and parts are cheap. Ask about gasket condition before you wear one near water, since 30 m of factory-rated resistance is nominal even on the genuine watch. A quartz copy runs until the battery dies and then goes in a drawer. Neither will hold value, and both should be priced as disposable goods rather than investments.