The core advice is simple: on the IW371633, the movement dictates everything. This reference is a vertical bicompax chronograph, so the two subdials sit at 12 and 6 with a date at 3. Copying that layout with a bought-in chronograph movement forces compromises in subdial spacing and case thickness, and those two things separate a wearable replica from an obvious one. Check dial layout and case profile first, then look at dial printing, hands and caseback. Treat engraving quality, packaging and the words "Swiss made" as decoration rather than evidence.
What the IW371633 actually is
The genuine watch is a stainless steel Portugieser Chronograph. Knowing the target numbers gives you something to measure against.
- Case: stainless steel, about 41 mm across, roughly 13 mm thick, 20 mm lug width
- Dial: vertical bicompax, small seconds at 6, chronograph minutes at 12, date at 3
- Hands: leaf shaped and polished, with applied Arabic numerals
- Crystal: domed sapphire with anti-reflective coating
- Movement: in-house column wheel chronograph, about 46 hours of power reserve
- Water resistance: 3 bar, which means splash resistance and not swimming
What to look for in a replica
Subdial position and spacing
This is the first thing to check. On the original, the subdial centers sit close to the vertical axis and the gap between each subdial and the date window is tight. Many replicas built around a modular chronograph movement push the subdials toward the case edge, which leaves a wide, empty band across the middle of the dial. Ask for a straight-on photograph with no tilt, then compare the distance from the case edge to each subdial. If the seller only supplies angled shots, that is usually deliberate.
Case thickness and profile
A modular chronograph stack adds height. Replicas often run one to two millimeters thicker than the original, and the extra depth shows in the lugs, which end up thick and flat instead of tapering. A watch that stands tall on the wrist and catches on a shirt cuff is the giveaway. If the case feels light for steel, suspect plated brass or an aluminum alloy rather than stainless steel.
Dial details
Look at applied numerals for uneven height and rough edges, at the printed minute track for blurred or doubled lines, and at the date wheel for a font that is too bold or a numeral that sits off center. Dial color shifts with light, so compare in daylight. Studio lighting hides mismatched tones.
Movement and pushers
A column wheel chronograph gives a light, consistent click at the pushers and a chronograph seconds hand that starts cleanly. A cam-actuated movement feels stiff and the hand often jumps on start. Ask directly what movement family is inside. A seller who cannot answer, or who answers only with the word "Swiss", is telling you something.
Caseback and engravings
Reference numbers, case numbers and movement decoration are easy to fake and easy to over-read. Rotor engraving and striped finishing are cosmetic. What matters is whether the movement matches the pusher feel and the power reserve you were promised.
Parameter bands worth measuring
- Diameter: 40.8 to 41.2 mm across the case, excluding the crown
- Thickness: 13.0 to 13.6 mm at the crystal, measured with calipers
- Lug width: 20 mm, measured between the lugs
- Subdial centers: close to the vertical axis, with a narrow band between them
- Power reserve: near 46 hours when fully wound
- Chronograph reset: both hands return to zero without drifting
Pitfalls to avoid
- Listings that use official press photos instead of shots of the actual watch
- Claims of 50 or 100 meters of water resistance on untested gaskets
- Casebacks marked "Swiss made" over an Asian movement
- Sellers who quote a grade or tier but never name the movement
- Buying across a border without checking the import risk, since counterfeit goods can be seized and the buyer can lose both the item and the money
- Assuming any watchmaker will service it. Many will not, and parts for modified chronograph movements can be hard to source
FAQ
How do I confirm the subdials are correct without the watch in hand?
Request a flat, head-on photo next to a ruler or a coin of known size. Measure the ratio of the subdial spacing to the case diameter and compare it with a photograph of the original shot the same way.
Will a genuine strap fit a replica?
If the lug width is a true 20 mm and the spring bar holes line up, yes. A decent leather strap is the cheapest upgrade you can make and it changes how the watch reads on the wrist.
Can a local watchmaker service it?
Some will, some will not. Ask before you buy, and ask which movement they would service. A watchmaker who has never seen the movement inside will not quote you a turnaround.
Does a replica hold value?
No. There is no resale market, no warranty and no factory service path. Buy it as a disposable object and the decision gets easier.
Is a decorated movement worth paying more for?
Only if the base movement and the chronograph architecture are right. Decoration on a badly spaced dial is money spent in the wrong place.