The short answer
A replica IW371615 is worth buying when it gets three things right: a 41mm case no thicker than about 13.5mm, a blue dial that shifts tone in changing light instead of sitting flat, and a movement that matches the layout of IWC's calibre 69355. Most cheap versions fail on thickness. If a seller cannot name the movement inside, assume the worst and keep looking.
What the real IW371615 is
IWC's IW371615 is the blue-dial version of the Portugieser Chronograph 41, introduced in 2020 when the line moved to the in-house calibre 69355. Stainless steel case, 41mm across, roughly 13mm thick, 30m water resistance. Bicompax dial: chronograph minutes at 12, small seconds at 6, date at 3. Leaf-shaped hands, applied numerals and indices, alligator strap on a steel pin buckle. That 2020 change is the whole game here, because the earlier Portugieser Chronograph ran a Valjoux-based movement and sat noticeably chunkier on the wrist.
Case and dimensions
The number I check first is thickness. Original is about 13mm. A replica running a modified 7750 usually lands at 14.5mm or more, and the caseback bulges in a way you feel against a shirt cuff. Top-tier replicas with a 69355 clone get within half a millimeter of the real thing.
Other points to compare side by side:
- Lug-to-lug, which should sit around 47mm and not overhang a seven-inch wrist.
- Pushers at 2 and 4, a signed crown, and chrono action that snaps rather than mushes.
- Finishing: brushed case sides, polished bezel and lugs, with a crisp line where the two meet. Polish that bleeds across the edges is a bad sign.
- Caseback engraving. Reference markings and branding should be sharp under a loupe, not shallow and fuzzy.
Dial and hands
Blue is hard to fake. The original dial reads nearly black indoors and turns a deep, slightly metallic blue in daylight. Cheap replicas go purple or washed out, and no amount of photography fixes that in person.
Check the two subdials. Both should show circular graining, and their hands should match the shape of the originals rather than using generic fillers. The date window at 3 should be cleanly cut with no ragged paint around the opening.
Printed text is where replicas get lazy. Look at the spacing between the logo and the lines beneath it. Lettering that crowds or touches is visible from a foot away.
Hands should be leaf-shaped, mirror polished, with a defined bevel. Tilt them under a lamp. Rounded, blobby tips on a watch that costs several hundred dollars are not acceptable.
Crystal, caseback, strap
The original crystal is domed sapphire with anti-reflective coating on both faces. Replicas often coat only one side, which shows up as a pale gray glare washing across the dial instead of a near-invisible surface.
The caseback is a sapphire display. Whatever movement you get will be visible, so movement finishing matters. A well-decorated clone often looks better through that window than a stripped-down Swiss-spec chrono module.
On the strap, the original is alligator. Replicas ship with embossed leather that looks synthetic at the edges. Budget for a replacement strap. It changes the whole watch more than any other single fix.
Price tiers
- Around $150 to $250. Wrong thickness, flat blue dial, 7750 movement. Fine as a beater, not a match.
- Around $300 to $450. Better dial and case, still frequently too thick. A reasonable middle option.
- Around $500 to $700 and up. Clone 69355, correct dimensions, sapphire front and back, dial that survives a hand check. This is where I would spend.
How to screen one in five minutes
- Ask for caliper photos of the case thickness, not just a side profile shot.
- Ask for video of the chronograph starting, running, and resetting to zero. Hands that drift off 12 on reset are a problem.
- Look at the dial indoors and outdoors. One flat shade only means cheap paint.
- Wind it and cycle the chrono. Gritty crown feel shows up immediately.
Bottom line
A replica IW371615 is not hard to find. A good one is. Pay for the movement and the case profile, not for packaging or vague country-of-origin claims. Get the thickness right and the blue dial behaving properly, and everything else is fixable with a strap and a short trip to a watchmaker.