The replica IW371789 worth your money gets the boring parts right. That means a 41 mm case close to 13 mm thick, subdials at 12 and 6 sitting where they belong, a leaf hand set with the correct curve, and a chronograph that runs off the pushers instead of a decorative dial. Dial color and strap are easy to live with. Case geometry is not.
What You Are Actually Matching
The IW371789 comes out of IWC's Portugieser Chronograph family, the round-cased, slim-bezel, wide-open-dial line that has been in near-continuous production for decades. That family history is the problem. Reference numbers in this range get reused across dial colors, strap options and boutique editions, so two watches that look unrelated on a table can share the same base caliber and case tooling.
Before you compare anything, pull the exact reference's spec sheet: case diameter, thickness, lug width, water resistance, dial color name, and whether that version carries a date. A copy can be well built and still be the wrong watch for your reference.
Case and Thickness
This is where most copies slip, and it is the first thing I look at. The genuine Portugieser Chronograph wears thin for a chrono because the movement is compact and the caseback is not doing anything clever. Many replicas hide a modified 7750 or a transfer module under the dial, and that stack adds half a millimeter or more.
Half a millimeter sounds trivial on paper. On the wrist it changes how the watch sits under a cuff and how the lugs taper into the strap. Put a caliper on it if the seller will let you. If they will not, ask for a side-on photo with a ruler.
Check the lugs too. They should curve down toward the wrist cleanly, with crisp edges and no rounding from over-polishing. Look at the bezel step where the case flank meets the top surface. On a cheap case that transition is soft and slightly smeared.
Dial and Hands
The Portugieser dial is uncluttered, which means errors have nowhere to hide.
- Subdial spacing. The 30-minute counter at 12 and the small seconds at 6 need to sit tight to the center. Copies built around a stock movement often push them outward.
- Numeral placement. Look at how the 12 and 6 sit relative to the subdial rings. A slight misalignment reads as sloppy from a foot away.
- Applied markers. They should be raised, with a clean bevel and consistent height around the dial.
- Leaf hands. The curve matters. Flat, stamped hands are an instant tell under any light.
- Print. Under a 10x loupe, hour and minute track printing should be sharp, with no ink bleed at the track ends.
Turn the watch slowly under a lamp. Good dial finishing shifts from matte to faint sheen. Flat paint stays flat no matter what angle you hold it at.
The Movement
Ask what is inside and expect a vague answer. Then test it yourself.
Start the chronograph and watch the 30-minute counter creep forward. Reset it and listen. A column wheel movement gives a light, clean pusher feel; a cam-actuated clone feels stiffer and can have a soft reset snap. Hacking matters too: pull the crown, and the seconds hand should stop dead.
The reset should return both hands to zero every single time. Do it five times. If one hand lands a hair off center, it will bother you later.
A Short Buying Checklist
- Confirm the exact reference details, including whether your version has a date aperture.
- Measure case thickness and compare it to spec.
- Photograph the dial straight on and check subdial symmetry.
- Run the chrono through several start, stop, reset cycles.
- Inspect the caseback engraving depth and the rotor finishing.
- Check the strap for real stitching and a proper buckle.
One Honest Note
A replica is not a substitute for the real thing, and it is not waterproof no matter what the caseback says. Treat 30 m as splash resistance at best. Selling counterfeits is also illegal in many countries, so know your local rules before you buy or resell.
Buy the version that gets the case and dial right. Everything else can be fixed later.