Short answer
A fake IW371487 is a replica of the IWC Portugieser Chronograph reference IW371487. The genuine watch is a 40.9mm stainless steel chronograph, roughly 12.5 to 13mm thick, with two subdials stacked at 12 and 6, no date window, sapphire crystals front and back, and IWC calibre 79350, a heavily reworked Valjoux 7750. Replicas of this reference run from about $80 for a throwaway quartz build to $400 or more for a so-called super clone, and almost none of them get the movement architecture right. If the seller cannot tell you which movement is inside, that is your answer.
What the real reference gives you as a yardstick
You cannot judge a copy without a baseline. The Portugieser Chronograph has a few traits that are hard to fake cheaply, and they are the same traits I check first when I look at photos of a replica.
- Case: 40.9mm wide in steel, with long slender lugs that curve down sharply. The whole silhouette is thin and flat, not chunky.
- Dial: applied Arabic numerals, leaf-shaped hands, a printed minute track, and subdials that sit deep in the dial rather than on top of it.
- Subdials: running seconds at 6, chronograph minutes at 12. No hour counter, no date, no extra windows.
- Movement: calibre 79350, a 7750 base running at 28,800 vph with a 44 hour power reserve. Newer Portugieser Chronograph references moved to the in-house 69355, so confirm the sheet for the exact reference you are looking at.
- Crystal: domed sapphire with anti-reflective coating on both faces, and a display back showing the movement.
The three replica tiers you will actually see
1. The $60 to $120 quartz tier
Battery powered. The chronograph pushers usually do nothing, or the subdial at 12 is a fake 24 hour hand. The case is thick and the lugs are wrong. The dial printing is flat and the subdials sit proud. Skip these unless you want a costume prop.
2. The $150 to $250 mid tier
Usually an Asian 7750 or a stripped automatic. The proportions improve, but the case is often 1mm too thick, the crown guards are wrong, and the subdial spacing drifts. It looks right from a meter and wrong from 30cm.
3. The $350 and up clone tier
These use a copy of the 7750 architecture, sometimes a genuine ETA or Sellita base, with correct 28,800 vph beat rate and a functional chronograph. Case dimensions get close. This is the only tier where the watch feels like a watch.
Details that give a fake away
- Subdial depth. On the real dial the two counters are recessed with a fine snailed texture. On copies they are often flat discs.
- Hand length. Subdial hands that stop short of the track, or overlap it, are a tell.
- Logo. The IWC wordmark should be applied metal, not printed ink. It should sit level and catch light.
- Lug shape. Straight, stubby lugs on a 40.9mm case look wrong instantly.
- Caseback engraving. Reference numbers, serial spacing, and depth of engraving are usually shallow on replicas.
- Movement finish. Cotes de Geneve striping, blued screws, and a signed rotor are easy to check through the display back.
Before you buy, run this checklist
- Ask for the movement name, beat rate, and power reserve. Vague answers mean a low tier build.
- Request photos on a plain background with the crown at 3, plus a wrist shot. Angles hide thickness.
- Ask for a short video of the chronograph starting, stopping, and resetting to zero.
- Confirm case width and thickness with calipers if the seller has them. 40.9mm and around 12.5 to 13mm is the target.
- Check the crystal for coating glare. Uncoated glass looks hazy at an angle.
- Ask about water resistance and assume the answer is no. Never swim in a replica.
One honest note
A replica is not a genuine IWC and it never will be. Selling one as authentic is fraud in most countries, and shipping counterfeits across borders carries real legal risk. If the goal is the look of the Portugieser Chronograph on a budget, buy it knowing exactly what it is, and never represent it as anything else.