The short answer: before you pay for a replica IW371651, pull up the genuine IWC spec sheet for that reference and compare it point by point, then inspect three physical details closely. The IW371651 belongs to the Portugieser Chronograph family, a bi-compax design with a small seconds hand at 6 o'clock and a 30 minute counter at 12. Replica makers usually get the silhouette close and lose the sale on subdial spacing, case thickness, and crystal clarity. Build your checklist around those three items and you filter out most weak stock in a few minutes.
What the reference number actually tells you
A reference number is a specification, not a style. Within the Portugieser Chronograph line, the case size, dial furniture, strap type, and movement generation change from one reference to the next. A seller who shows you photos of one variant and ships another has already told you how the rest of the transaction will go. Ask for the reference number in writing, then ask for photos of the caseback engraving, the dial at an angle, and the watch on a scale. Numbers and photos together are hard to fake in real time.
What to inspect before you buy
- Subdial spacing. On the original, the two counters sit close to the center with narrow gaps at 12 and 6. Cheap builds push them out toward the edge because the movement underneath is the wrong size.
- Dial printing. Look at the letter spacing in the brand name and the thinness of the minute track. Thick, blobby print is the single easiest tell in a photograph.
- Crystal. You want sapphire or a convincing sapphire substitute with coating that kills glare without a blue or purple hue at an angle.
- Pusher feel. Chronograph pushers should click with a short, firm travel. Mushy or gritty pushers point to a cheap module stacked on a basic movement.
- Caseback engraving. Depth, font, and alignment matter. Shallow laser etching on a smooth surface reads as costume jewelry.
- Weight and balance. A watch this size should feel dense in the hand and sit flat on the wrist, not tip toward the crown.
Numbers worth memorizing
Ask the seller for these and compare against the official figures for the exact reference you are considering.
- Case diameter: roughly 41 mm for this generation
- Case thickness: about 13 mm, and anything noticeably thicker will wear wrong
- Lug width: 20 mm, which affects how aftermarket straps fit
- Movement type: automatic chronograph with a column wheel, about 4 Hz, roughly 46 hours of reserve
- Crystal: domed sapphire with anti-reflective treatment
- Water resistance: low, typically 3 bar, so treat it as splash resistant only
Common traps in the replica market
- Quartz movements sold as automatic. If the seconds hand ticks once per second instead of sweeping, stop there.
- Stock photos reused across listings. Reverse image search the pictures before you commit.
- Grading labels with no definition. Terms like first copy, AAA, and super clone mean whatever the seller wants them to mean that week.
- Pressure to pay outside a protected method. Chargebacks are your only real recourse.
- Claims about Swiss origin. Swiss Made labeling rules are strict, and replica dials routinely misuse the wording.
Legal and practical reality
Counterfeit watches are restricted goods in the United States and many other countries, and customs can seize an import. That risk sits with the buyer, not just the seller. Treat any purchase as a novelty item, expect no warranty and no service support, and do not plan on resale value. If you want a watch you can actually have serviced, a hommage style piece from a legitimate brand at a similar size is the safer route and often costs less than the top replica tiers.
FAQ
How can I tell a fake IW371651 from the real thing in photos?
Compare subdial positions, dial printing weight, and crystal reflections against official product images at the same angle. Most replicas fail on at least one of those three.
Does the movement really matter at this price level?
Yes. A sweeping automatic with a working chronograph and a column wheel feels completely different from a quartz watch with decorative subdials, and it affects how long the watch lasts.
Should I buy from a listing with only stock images?
No. Request dated photos of the actual unit, including the caseback, crown, and pushers, before sending any payment.
What is the biggest single mistake buyers make?
Buying the silhouette instead of the specification. A watch that looks right on a thumbnail but measures 2 mm too thick will feel wrong every time you wear it.