The IW371775 is a stainless steel IWC Portugieser Chronograph. A replica of it stands or falls on three things: case size, dial layout, and the movement behind the caseback. Nail the first two and the watch reads as convincing at arm's length on the wrist. Miss the third and the chronograph gives itself away inside a day. This guide lists what to check, in order, before money changes hands.
Baseline specs for the reference
IWC builds the Portugieser Chronograph around a 41 mm stainless steel case, roughly 13 mm thick, with a two-register dial and an in-house automatic chronograph calibre in the 69000 family. Water resistance is rated at 30 m, the crystal and caseback are sapphire, and the strap is alligator on a signed pin buckle. Two subdials sit on a vertical axis: elapsed chronograph minutes at 12 o'clock, running seconds at 6. There is no date window. Those numbers are your measuring stick. A replica that misses them by a millimeter or a millimeter and a half looks wrong from across a table, even to someone who has never handled the real thing.
Prerequisites
- A digital caliper that reads to 0.1 mm.
- A 10x jeweler's loupe.
- A phone with macro mode for dial and caseback photos.
- The seller's return window in writing, with the inspection period stated in days.
How to inspect a replica IW371775
- Measure the case before you look at anything else. Diameter should land at 41 mm, thickness near 13 mm, and lug width at 20 mm. Copies that run 42.5 mm wide or 15 mm thick throw the proportions off, and no amount of dial work hides that.
- Count the subdials and note where they sit. One at 12 for chronograph minutes, one at 6 for running seconds, nothing at 3. A date aperture is an automatic fail on this reference.
- Read the dial print with the loupe. The minute track should be sharp and unbroken, with numerals applied and polished rather than stamped flat into the surface.
- Check the hands. Leaf-shaped hands with clean edges, gold tone that matches across hour, minute, and subdial hands, and subdial hands long enough to reach the track they point at.
- Run the chronograph. Start it, let it run past the 60-second mark, then stop. The counter at 12 must advance one position. Reset and confirm both hands snap back to zero without drifting.
- Study the case finishing under raking light. Brushed top surfaces, polished flanks, crisp lug bevels. Look for wavy polish, rounded edges, tool marks, and gaps where the bezel meets the midcase.
- Examine the crystal. Lightly domed sapphire with anti-reflective coating, and no strong blue or purple glare when you tilt it toward a light source.
- Turn it over and inspect the caseback engraving. Reference and serial numbers should be cut with even depth and consistent spacing, not laser-etched pale gray. Inside, check the rotor engraving, the striping, and the screw heads.
- Confirm the beat rate. Hold it to your ear or run a timegrapher app: 28,800 vibrations per hour is correct. A slower 21,600 tick points to a hand-wound Seagull movement, and a single tick per second means quartz.
- Check the strap and buckle. Alligator grain with a taper that matches the lug width, and a pin buckle with engraving as deep as the caseback marking.
Movement tiers and what they cost you
The movement decides how the watch behaves in daily use. A modified 7750-based automatic gives you the correct sweep, a working minute counter, and a rotor that winds both ways. A hand-wound Seagull chronograph keeps the dial side correct but loses the automatic winding and the caseback look. A quartz build is the cheapest route and the easiest to spot, because the seconds hand at 6 o'clock jumps once per second instead of sweeping. Ask the seller which movement is fitted and treat a vague answer as a no.
Red flags
- Subdial spacing that crowds the center or leaves a gap at the edges.
- Printed indices instead of applied metal markers.
- Lug edges sharp enough to catch a cloth.
- A caseback that is solid steel on a reference that ships with a display back.
- Stock photos only, with no image of the actual unit on offer.
Legal note
A replica is not an IWC product, and it carries no warranty from the brand. Counterfeit goods are subject to seizure at the border and to civil penalties in the United States, so treat the purchase as a legal risk rather than a routine transaction. Anyone selling a copy as genuine commits trademark infringement and fraud.