The short answer
The reference is real. IW371613 sits inside the IWC Portuguese Chronograph 41 family: a 41 mm steel chronograph with two subdials, no date, and the in-house caliber 69355 inside. Anything sold as an "IW371613" for a few hundred dollars is a replica, and what separates a decent first copy from junk is rarely the logo. It comes down to thickness, the crystal, the dial print, and the caseback engraving. Check those four and you will know what you are holding inside a minute.
What the genuine watch gives you as a baseline
Before you judge a fake, fix the real specs in your head.
- Case: stainless steel, about 41 mm across, roughly 13 mm thick.
- Dial: two registers. Chronograph minutes at 12, running seconds at 6. No date window anywhere.
- Movement: caliber 69355, automatic, column wheel chronograph, about 46 hours of reserve.
- Water resistance: 3 bar. That is splash resistance, not swimming.
- Crystal: box-shaped sapphire with anti-reflective coating on both sides.
Those numbers matter because a fake fails on the details nobody photographs. Diameter is easy to copy. Thickness is not.
The four checks that expose most fakes
1. Thickness and side profile
Most mid-tier replicas run 1 to 2 mm too thick, and it shows in how the watch sits. Put a caliper on it if you can. Failing that, look at the caseband. The real one has a slim, straight flank and short lugs that curve down. A thick fake looks like a puck on the wrist, with lugs that sit flat instead of wrapping.
2. The crystal
Genuine sapphire with double-sided AR coating nearly disappears at an angle. You get a faint blue or purple tint and very little reflection. Cheap fakes use mineral glass, which throws a white glare back at you and shows a heavy dome edge. Run a fingernail across the surface too. Sapphire feels slick and cold. Mineral glass has a softer, grippier feel.
3. Dial print and subdial spacing
Get close with a loupe or a phone macro shot. On the real dial the numerals are applied, the print is sharp with no ink bleed, and the two subdials sit on a clean vertical line with even spacing. Fakes show fuzzy edges, numerals that sit slightly crooked, and subdials pushed a hair off center. Watch the subdial at 6 while the chronograph is idle. It should be the running seconds. On lazy builds it is a chronograph hour counter, or it does not move at all.
4. Caseback engraving
Reference number, serial, and the IWC markings are engraved on the real thing with crisp edges and consistent depth. Fakes usually show shallow, rounded lettering, or they reuse the same serial across every unit. Ask the seller for a photo of the back and compare that serial with anything else they have listed. Duplicate serials are the oldest giveaway there is.
Where cheap copies cut corners
- Pushers that feel mushy or need a hard press. A column wheel movement should start and reset with a light, even click.
- Straps with plastic-looking edge paint and stitching that wanders off the line.
- Buckles stamped instead of engraved, with the logo sitting off center.
- Rotor and bridge finishing that looks rough, if you can see the movement at all.
- Crowns that are too small or too tall for the case, so winding feels gritty.
What "first copy" actually means
The term covers a wide range. At the bottom you have quartz builds with a decorative dial and a battery inside. In the middle sits the 7750-clone crowd, where the chronograph works but the movement has been modified in a hurry. At the top you get a smooth automatic chronograph, the correct subdial layout, properly applied markers, and a case within a fraction of a millimeter of the original. Price tracks that ladder almost exactly, so treat an unusually low number as information, not luck.
Questions to ask before you pay
- What is the exact case thickness in millimeters?
- Which movement is inside, and is it automatic?
- Which subdial runs when the chronograph is stopped?
- Can you send real photos of this specific unit, not catalog shots?
- What is the return window if the watch arrives damaged?
A seller who answers all five without hedging is usually selling the tier they claim. A seller who dodges the thickness question is telling you something too.
FAQ
Does the real IW371613 exist?
Yes. It is one of the Portuguese Chronograph 41 references, so a search for "fake IW371613" is about copies of a real watch, not a made-up model number.
Can a jeweler spot a first copy?
On a bench, yes, if they open the case and study the movement. On the wrist, at arm's length, usually not. That is the honest answer for any high-tier replica.
Is wearing one legal?
Owning a replica is generally not the issue. Selling one as genuine, or importing counterfeits in commercial quantities, is a different matter, and customs agencies treat it that way.