The short answer: a fake IW371470 is a replica of IWC's stainless steel Portugieser Chronograph, and the quality spread is huge. The cheap end is a generic chronograph in a soft case with a printed dial. The top end copies the case dimensions, dial layout and crystal closely enough that only a loupe or a jeweler's bench reveals it. The middle is where money gets wasted, because you pay real-watch money for something that still has the wrong movement and the wrong finishing.

What the genuine IW371470 is

Ref. IW371470 belongs to the Portugieser Chronograph family, the two-register model IWC has built across two generations. Picture 41 mm of stainless steel (IWC lists 40.9 mm), a thin bezel, leaf-shaped hands, applied numerals, chronograph minutes at 12, running seconds at 6, and a date window at 3. Sapphire covers the dial; depending on the generation the caseback is either solid with engraving or a display back. Earlier watches in the family ran on caliber 79350, a reworked Valjoux 7750. Later ones use the in-house 69355. Which generation a seller claims to copy changes what you should expect from the movement inside.

Where replicas get close

The better factories CNC the case from a scan of a genuine watch, so the diameter, lug curve and crown position land within a fraction of a millimeter. The dial layout is easy to copy and usually is. You get sapphire front and back, an anti-reflective coating on the inside, a decent alligator-grain strap and a folding clasp that feels solid. On the wrist, at arm's length, in a room, it reads as a Portugieser.

The tells that still give it away

• Thickness. Most replicas are half a millimeter to a millimeter thicker than the genuine case, and you feel that more than you see it.
• Dial printing. The weight of the "IWC" and "Schaffhausen" text, the crispness of the rail track and the rings around the subdials are all slightly off on anything below the top tier.
• Subdial hands. Genuine counters use leaf-shaped hands. Replicas often use plain batons.
• Movement finish, on display-back versions. Cotes de Geneve stripes and perlage that look painted rather than cut, and rotor engraving that is laser etched instead of properly engraved.
• Caseback engraving. Reference numbers, the Probus Scafusia mark and the ring of text are shallower and less sharp.
• Chronograph feel. Genuine pushers have a short, firm throw, and the chronograph hand snaps back to 12 every time. Replicas often land a hair off center or feel mushy.
• Rotor noise. Shake a replica and you hear it. A genuine 69355 or 79350 is quiet.

Movements and what they mean for ownership

Most replicas of this reference run a modified Asian 7750, which is why the subdial layout works and why the chronograph functions at all. It beats at 28,800 vph and keeps time fine out of the box, but the power reserve in practice is usually shorter than the 44 to 46 hours IWC quotes, the rotor is louder, and servicing is a problem. Independent watchmakers often refuse to touch replicas, so when it stops you replace it rather than repair it. Water resistance is nominal. Do not swim with one, no matter what the listing claims.

Price tiers

Under about $150 you are buying a costume piece; the dial printing, the case finish and the movement all show it. Between roughly $250 and $500 you get the decent tier, with a proper case, sapphire and a working chronograph. Above $600 you are in super clone territory, where the differences come down to movement decoration, dial text weight and the quality of the strap. Past that point the money stops buying accuracy and starts buying marketing.

If you are checking a watch you already own

Start with the caseback. Genuine engraving has depth you can feel with a fingernail. Then look at the chronograph: start it, let it run a minute, reset it, and see whether the hand returns dead on 12. Check the crown action. Push the crown in and out; a genuine IWC feels precise, not gritty. If the seller cannot show you a movement photo, a timegrapher reading and a video of the reset, walk away.

Bottom line

A fake IW371470 can be a fun $300 watch. It is not an investment, it will not hold value, and most watchmakers will not service it. If you want the real thing, buy a used genuine from a seller with papers, or spend the same money on a brand that makes a two-register chronograph at that price. If you buy the replica, buy it knowing exactly which of those two things you are doing.