A fake IW371618 is a replica of the IWC Portugieser Chronograph reference 371618, a 41 mm steel chronograph from the 3716 family. The fastest way to separate a replica from the genuine watch is the dial printing and the geometry of the two subdials, followed by the movement finishing visible through the sapphire caseback. Everything else, from the pusher feel to the strap stitching, confirms what the dial already told you.

What the reference number tells you

The 3716 series replaced the older 3714 Portugieser Chronograph and moved the line to an in-house chronograph caliber with a vertical subdial layout: running seconds at 6 o'clock and a 30-minute counter at 12, with the date at 3. Any listing for an IW371618 that shows a different subdial arrangement is not a watch you need to inspect further. Because the reference sits inside a large family of dial and strap combinations, the number alone does not describe the dial color, so always compare the seller's photos against the official reference page for that exact variation.

Dial and printing: where most fakes fail

Dial work is expensive, and it is the part of a replica that factories struggle to match. Look at these areas in order.

  • Logo and text weight. The IWC wordmark, the Schaffhausen line, and the "Automatic" text should be crisp, evenly spaced, and printed at a consistent depth. On a poor fake the lettering looks slightly bold, slightly soft, or crowded against the subdial.
  • Subdial spacing. The two counters should sit on a clean vertical axis with equal margins from the center. Replicas built on a modified third-party chronograph movement often push one counter a fraction off center, which is easiest to see in a straight-on photo.
  • Applied indices. Genuine markers are cut and polished with sharp edges and sit flat against the dial. On replicas they can look rounded, unevenly polished, or lifted at one corner.
  • Date window and font. The aperture should be cleanly cut with no burr, and the numeral should fill the window without touching the edges. A date font that looks generic is a common tell on a fake IW371618.
  • Hand finish. Leaf-shaped hands should be flat and reflective, with no visible machining marks under a loupe or a phone macro shot.

Case, crown, and pushers

The 3716 case has a slim bezel and long, curved lugs, and the proportions are hard to fake without the right CNC work. Check the lug profile from the side: it should taper smoothly and return cleanly to the case, with brushing that runs in one direction and polished edges that stay sharp rather than washed out. The crown should be engraved deeply enough to catch a fingernail, and the two chronograph pushers should travel with a firm, short action. Mushy pushers or a crown that wobbles are signs of a budget build, not a premium 1:1 replica.

Case thickness is worth measuring if you can. Replicas that add a chronograph module on top of a standard movement often end up noticeably thicker than the genuine watch, and the extra depth shows up on the wrist and in profile photos.

Movement and caseback

The genuine watch runs an in-house IWC chronograph caliber, and that is the hardest component to copy. Replicas typically use either a decorated third-party chronograph or a clone built to resemble the original. Through the sapphire back, judge the finishing of the bridges, the depth of the engravings, and the presence of sharp bevels. A rotor with shallow laser etching, flat blued screws that are painted rather than heat-treated, and uniform matte surfaces all point to a replica.

Function matters as much as looks. Start the chronograph, let it run for a minute, then reset. The seconds hand should snap back to zero in one motion and the minute counter should follow. Hesitation, a hand that lands slightly past zero, or a reset that requires a second press are mechanical warnings.

Strap, clasp, and packaging

Genuine IWC straps are firm and evenly stitched, with a cleanly embossed logo on the underside and a signed pin buckle or deployant clasp. Replica straps often feel softer out of the box, use coarser thread, and have a faintly stamped logo. Boxes and papers are the easiest things to fake, so never treat a full set as proof of authenticity. A fake IW371618 can arrive in convincing packaging and still be wrong where it counts.

A short checklist before you commit

  1. Confirm the subdial layout matches the 3716 family, with counters at 12 and 6.
  2. Ask for a straight-on dial photo and a macro of the logo and date window.
  3. Request a movement photo through the caseback and compare engraving depth.
  4. Ask for the case thickness and the lug-to-lug measurement.
  5. Check the chronograph start, stop, and reset behavior on video.
  6. Compare the asking price against the market for the genuine reference, and treat unusually cheap "authentic" listings as a warning.

Where replicas still fall short

A high-end replica IWC Portugieser Chronograph can look convincing on a table, and modern finishing has closed much of the gap on the case and dial. The remaining differences sit in the movement architecture, the crispness of the printing at macro distance, and the long-term consistency of the chronograph mechanism. Buyers who understand those limits get a wearable watch that photographs well; buyers who expect a genuine watch at a fraction of the price end up disappointed. Use the dial, the subdials, and the movement as your three checkpoints, and the decision becomes straightforward.