If someone is offering an IW371761 for a few hundred dollars, it is a replica. The reference belongs to IWC's Portugieser Chronograph 3717 family, a steel watch that has held four figure resale value for years, and nobody sells a real one for pocket money. So the useful question is not whether the watch is fake. It is which kind of fake you are looking at: a cheap quartz lookalike, a mid tier Asian chronograph with a decorated rotor, or a good replica that nails the proportions and only fails under a loupe.
I look at fakes of this reference in a fixed order: movement first, then dial, then case and caseback, then the accessories. That order matters because the movement is the hardest thing to copy well and the easiest thing to check.
Start with the movement, not the dial
The genuine 3717 runs IWC caliber 79320, a heavily reworked Valjoux 7750. Two things matter here. First, the running seconds sits in the subdial at 6, and the chronograph minutes counter sits at 12. A stock 7750 does not do that, which is why the layout is such a good filter. Plenty of fakes wire the lower subdial to the chronograph, or put a 12 hour totalizer where running seconds should be.
Second, look at how the chronograph behaves. Start it, let it run, reset it. The pushers on a real 79320 have a firm, short travel with a clean click, and the reset snaps back hard. Mushy pushers with long travel are a bad sign. The date should flip with a crisp jump at midnight, not drag slowly for two hours.
One thing I would not use as proof either way: the rotor wobble. The 7750 family has a heavy oscillating weight that you can feel when you move your wrist, and good clones reproduce that feel. Wobble alone tells you almost nothing.
Dial printing and hands
The Portugieser Chronograph lives or dies on small details, which is exactly where replicas get lazy.
- Leaf hands should have a subtle convex curve along the length and crisp edges. Fakes tend to look flat, or too thick where the hand meets the pinion.
- The applied numerals at 12 and 6 should be polished, faceted at the edges, and sit tight to the dial with sharp shadows.
- The wordmark and the city name must be sharp at 10x. On fakes the strokes look bolder, the letter spacing drifts, or the print sits slightly raised and glossy.
- The railroad minute track should have even spacing and dots that line up with the markers. Crooked dots are common on cheap copies.
- The subdial rings should show fine, consistent concentric snailing. Coarse grooves or a plain flat ring means someone cut a corner.
Case, crown, and caseback
The 3717 case measures about 40.9 mm across and sits around 12 mm thick. Replicas often run 42 mm or more and feel chunkier on the wrist. Check the lug profile: the real watch has a polished bevel that catches light as a continuous line, and the brushing on the case sides runs one direction only.
The crown should carry a deep, clean engraving of the Probus Scafusia mark. Shallow or blank crowns are a giveaway. Flip the watch over and read the engraving with a loupe. Genuine caseback text is cut deep enough that the edges look sharp under angled light. Laser etching on fakes looks grey, flat, and slightly fuzzy at the edges. The reference and serial numbers should be legible, correctly formatted, and consistent with the paperwork.
Strap, clasp, and the box set
Later 3717s shipped on Santoni straps, earlier ones on standard alligator. Either way, look for a proper lining, even hand stitching, and clean edge paint. Most fakes arrive with embossed calf pretending to be alligator, and the pattern repeats in an obvious grid once you know what to look for. The deployant clasp should close with a solid click and show crisp engraving on the inside.
Paperwork is where fake sets fall apart fastest. Compare the fonts on the warranty card, the booklet, and the outer box. They should match. A full set that has three different typefaces is not a full set.
Let the price do the work
Used 3717s trade in the mid four figures depending on variant, condition, and whether the service history is documented. If a seller wants under about fifteen hundred dollars for a complete set, the watch is fake, stolen, or broken. There is no fourth option.
Before you commit, verify the exact IW371761 configuration on IWC's own reference data, since dial and strap combinations vary across the 3717 line and a mismatched combination is itself a red flag. Then ask for a short video: chronograph start, stop, reset, and a date change at midnight. Sellers who refuse are telling you something.
Quick check list
- Running seconds at 6, chrono minutes at 12.
- Firm pushers with a sharp reset snap.
- Sharp printing at 10x, no glossy raised lettering.
- Fine concentric snailing on both subdials.
- Case close to 40.9 mm, not 42 mm or more.
- Deep caseback engraving, legible serial and reference.
- Signed crown with a crisp Probus mark.
- Real alligator strap, matching fonts on all paperwork.
- Price that matches the real market.
If you actually want a first copy
None of this is a reason to feel bad about buying a replica. It is a reason to buy one that is sold honestly as a replica, at a replica price, from a seller who tells you what movement is inside. The problem starts when a replica is dressed up as genuine. That is fraud, the price jumps tenfold, and you have no recourse when the chronograph stops resetting to zero. Buy the copy as a copy, and check it with the same list above.