Quick answer
Comparing components on an IW371408 replica comes down to four checks: measurements, dial printing, hand finishing, and movement architecture. Calipers and a 10x loupe settle most questions in under ten minutes. The movement is the hardest part to fake, because the genuine Portugieser Chronograph runs a column-wheel chronograph, and most replicas carry a cam-switched clone of the Valjoux 7750 family.
Prerequisites
- Digital calipers with 0.01 mm resolution
- 10x jeweler's loupe or a macro lens
- Digital scale accurate to 0.1 g
- Verified reference photos of the exact IW371408 dial, hand, and strap combination
- Soft cloth and a spring bar tool
How to compare the components
- Read the reference number on the caseback, then match the dial color, hand color, and strap option against a verified photo of that same reference.
- Weigh the watch head without the strap and record the number. A steel case of this size should land within a few grams of the published figure, so a large deviation points to a plated brass or hollow case.
- Measure the case diameter at 2 to 4 o'clock, then again at 8 to 10 o'clock, and note any difference. The genuine case measures close to 41 mm across and stays within a tenth of a millimeter at every point.
- Measure total thickness at the center of the caseback and at the bezel edge. A clone movement with a thick rotor spacer usually adds 0.5 mm or more.
- Measure lug to lug and the gap between the lugs. Strap width should sit at 20 mm with no gap on either side of the spring bars.
- Hold the crystal at an angle to a lamp and look for the blue-violet tint of an anti-reflective coating on both faces. A single-sided coating throws a strong reflection from the dial side.
- Inspect the dial print under the loupe, checking the weight of the IWC letters, the spacing of the railway minute track, and the sharpness of the subdial rings at 12 and 6 o'clock.
- Lay a straightedge across the dial and compare subdial centers. The 30-minute counter at 12 and the running seconds at 6 must sit on the vertical center line.
- Check the hands for a faceted, mirror-polished top surface and a flat, grained underside. Painted or uniformly brushed hands are a tell.
- Look for a date window. This reference has none, so any aperture at 3 or 4:30 is an automatic fail.
- Wind the crown ten turns, then press each pusher. Start, stop, and reset should each give one clean click with no grit, and reset should snap the chronograph hand to zero without overshoot.
- Study the caseback engraving under the loupe. Genuine engraving has crisp, V-shaped walls at uniform depth, while laser etching looks shallow and rounded.
- Run the chronograph for one hour and time the running seconds against a quartz reference. A clone movement often drifts several seconds over that span.
- Turn the watch over and check the brushing direction on the lug tops, the polish on the bezel chamfer, and the grain of the caseback ring. Finishing that changes direction mid-surface is a replica marker.
- Remove the strap and inspect the spring bars, lug holes, and caseback gasket seat. Clean, centered holes and a seated gasket indicate a case built to a real specification.
Component reference points
Case and bezel
The genuine case carries a slim, concave bezel with a polished chamfer that meets a brushed caseband. Replica cases often show a wider bezel, softer lug bevels, and a caseband brushed in one direction only. Check the lug profile from the side: the genuine lug tapers with a visible change from brushed top to polished flank.
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Dial and printing
Dial printing is where most replicas lose points. The genuine railway minute track is fine and even, applied numerals sit flat with sharp edges, and the subdial rings are printed at a consistent thickness from edge to center. Look for fuzzy serifs on the IWC logo, uneven spacing between the 12 and 6 o'clock subdials, or a dial that reads gray rather than silver in indirect light.
Hands and crystal
Leaf-shaped hands should show a polished facet that catches light along its full length. The crystal sits nearly flush with the bezel on the genuine watch and shows very little reflection because of dual anti-reflective coating. A replica crystal usually stands proud of the bezel or shows a heavy blue tint from one side.
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Movement
IWC moved the Portugieser Chronograph from the Valjoux 7750-based calibre 79350 to the in-house 69355 column-wheel movement, so the production year of the reference you are comparing matters. Look through the caseback: a column wheel and vertical clutch layout differs visibly from a cam and lever stack. Open casebacks on replicas rarely align the rotor, the engraving, and the jewel count at the same time.
Caseback and strap
Engraving depth, font weight, and serial placement vary between production runs, so compare against a photo of the same batch. On the strap side, check the deployant clasp for crisp engraving on the blade and a smooth, even closing click. Alligator grain that flattens at the lugs instead of rolling indicates a stamped leather substitute.
Red flags
- Case thickness above roughly 13 mm on a slim chronograph case
- A date aperture on a no-date reference
- Yellow-green lume instead of an off-white or cream tone
- Subdials that sit off the vertical center line
- Pushers that feel mushy or reset with an overshoot past zero
- Caseback text with rounded edges and shallow depth
Limits of a visual comparison
Component checks identify obvious flaws, but they cannot confirm the alloy of the case, the origin of the movement, or the quality of the internal gaskets. Treat the caliper, scale, and loupe results as screening tools, and use a timing machine plus a pressure test when waterproofness and rate accuracy actually matter to you.