The short answer
IW371654 is the reference for the 41mm stainless steel Portugieser Chronograph with a blue dial and a rubber strap. Replica versions cover a wide range, from quartz-driven lookalikes to builds that copy the case, dial and movement layout well enough to hold up at arm's length. A mid-tier replica gets the look right. A top-tier replica gets the proportions and the chronograph action right. Nothing cheap gets either one.
What the genuine watch is
The Portugieser Chronograph 41 arrived as a reworked version of IWC's long-running Portugieser Chronograph, and the big change was the movement. The 41mm steel case is about 13.1mm thick, polished on the sides, with a sapphire crystal up front and a display back. Inside sits the in-house caliber 69355, an automatic column-wheel chronograph with a 46-hour power reserve running at 4Hz.
The dial is the part people recognize. A blue sunburst finish, applied numerals, leaf hands, and two subdials: a 30-minute counter at 12 and running small seconds at 6. The date sits at 3. The numerals at 12 and 6 get partly swallowed by the subdials, and that overlap is one of the hardest details to fake well.
Three tells that separate a good replica from a bad one
Case thickness and profile
This is the first thing I check and the fastest way to spot a budget build. A Valjoux 7750-based chronograph module adds height, and many replicas end up at 14.5mm or more against a genuine 13.1mm. Two millimeters does not sound like much until the watch is on a wrist. A top-tier replica uses a thinner movement or a reworked caseback to land within half a millimeter. Look at the side profile in photos, not just the dial.
The 9 o'clock subdial problem
The 7750 has three subdial positions: 12, 6 and 9. The Portugieser uses only two. Cheap replicas either leave a blank circle at 9 or, worse, wire the running seconds there and leave the 6 o'clock subdial dead. On a correct replica, the subdial at 6 sweeps as the running seconds and the one at 12 counts chronograph minutes. Ask for a video with the chronograph started. It takes ten seconds to confirm.
Dial, printing and date wheel
Genuine dials have a deep blue with a sunburst that shifts toward near-black at an angle. Replicas often land on a flatter, more purple blue. Check the weight of the printed minute track, the sharpness of the applied numerals, and the date font. A fat, generic date font on a white disc is a giveaway under a loupe, though not across a table.
Movements you will find inside
- Meca-quartz or quartz: smooth sweep is missing and the pushers feel hollow. Cheap, reliable, and easy to spot.
- Decorated Asian 7750: the most common option. Works, but thicker, noisier rotor, and the subdial layout needs correcting.
- Clone 69355 or reworked column-wheel chronograph: the top tier. Pusher feel is crisper, thickness is closer to real, and the caseback decoration will at least resemble the genuine bridge layout.
Ask which movement is inside before you compare prices. Two replicas that look identical in photos can sit hundreds of dollars apart because of this one part.
What each tier gets you
- Budget: right silhouette, wrong thickness, flat dial color, questionable water resistance.
- Mid: good case shape, correct dial layout, decent bracelet or strap, movement that keeps time but feels coarse.
- Top: near-correct thickness, sharp printing, working chronograph with a firm reset, sapphire crystal on both sides.
Checks before you commit
- Confirm the subdial at 6 runs as small seconds.
- Ask for the measured case thickness, in millimeters, not a photo caption.
- Watch a video of the chronograph starting, stopping and resetting to zero.
- Check that the date flips cleanly at midnight rather than drifting.
- Verify crystal material. Sapphire should feel cool and resist a light fingernail tap better than mineral glass.
- Look at the crown engraving and the caseback text under magnification.
- Confirm strap hardware, since rubber straps on replicas are where corners get cut first.
Questions that come up often
Will the chronograph work properly?
On anything above budget tier, yes. The reset is the tell. A good one snaps back to 12 without hesitation, and the pushers have a defined click rather than a mush.
Should I wear it near water?
Treat water resistance as unverified unless the seller states a tested rating. Gaskets on replicas are the first thing to age, and a 3 bar rating on a real Portugieser is not much protection anyway.
Can a replica be serviced?
A 7750-based replica can be serviced by most independent watchmakers, since the movement is a known design. A clone of a newer in-house caliber is harder to source parts for, so ask about that before buying.
Bottom line
The replica IW371654 is worth buying only when the thickness, the two-subdial layout and the dial color all line up. Get those three right and most people will never look twice. Get them wrong and no amount of polishing on the case will hide it.