The safest pick for a fake IW371613 is a high-tier replica built around a decorated clone of the IWC 69355 chronograph movement, with a working sapphire display caseback, a 41 mm case that matches the genuine proportions, and applied numerals set at the correct height. That recommendation rests on five checks: movement architecture, caseback transparency, dial printing and markers, case size and finish, and the feel of the pushers and crown. Run them in that order and most bad listings fall away before you ever discuss payment.
The short answer
Most fake IW371613 listings fail on the back of the watch. The genuine reference belongs to the current Portugieser Chronograph generation, which uses a display caseback, so a solid steel back is the fastest tell and usually signals a lower tier. The second tell is the chronograph itself: the real watch runs an in-house column wheel movement, and replicas built on a Valjoux 7750 base feel different at the pushers, with a softer start and a different reset snap. The third tell is the dial, where subdial spacing, print weight and the height of the applied numerals give a replica away in photos far more often than the case shape does.
What the genuine reference actually is
The IW371613 sits inside the 3716 Portugieser Chronograph family, so the line's architecture is your baseline. Confirm the exact dial colour and strap of your specific reference against official images, since the same case and movement appear with several dial variants.
- Roughly 41 mm case, close to 13 mm thick, with a slim bezel and long lugs
- In-house calibre 69355, column wheel chronograph, about 46 hours of power reserve
- Sapphire crystal front and a sapphire display back
- Two subdials: small seconds at 6 o'clock, chronograph minutes at 12 o'clock
- Applied Arabic numerals and leaf-shaped hands
Check 1: Movement and caseback
Ask for a clear, well-lit photo of the movement through the back glass before anything else. Decoration quality separates the tiers more than any other single factor.
What a good replica gets right
- Visible decorated bridges with a rotor that carries engraved text in a believable font
- Correct subdial function: the 12 o'clock counter should measure chronograph minutes, not replicate the seconds hand
- Rotor spin that is smooth and quiet when the watch is turned
Where replicas usually fail
- Wrong balance bridge shape or an obviously printed rather than engraved rotor
- Chronograph seconds that stutter instead of sweeping when started
- A solid caseback used to hide a basic movement
Check 2: Dial and hands
Look at the numerals first. Applied markers should sit proud of the dial with clean edges and a polished bevel, and the print on the chapter ring should be thin and even. Leaf hands should have a visible centre crease rather than a flat stamped profile. On the subdials, check that the rings are recessed slightly and that the snailing or concentric finish is visible at an angle. Flat printed subdials are the most common shortcut.
Check 3: Case, crystal and dimensions
Ask for the measured case diameter and thickness with calipers in the photo. A replica that measures 42 mm or more, or that comes in well under 13 mm thick, is not built to the right proportions. The crystal should be slightly domed with a colourless edge and minimal reflection. Lug finishing should be consistent on both sides, with brushing that runs in one direction and polished bevels that catch light evenly.
Check 4: Pushers, crown and winding
This is where a hands-on inspection beats any photo set. The start pusher on a column wheel movement has a short, crisp travel. Winding should feel smooth with no gritty spots, and the crown should seat flush against the case without a visible gap. If you are buying remotely, ask the seller to describe the pusher feel and to send a short video of the chronograph starting, stopping and resetting to zero.
Check 5: Strap and clasp
Strap quality is the cheapest thing for a seller to downgrade, and it changes how the watch wears more than most buyers expect. Look for stitching that is even and tight, edge paint without gaps, and a buckle or deployant with crisp engraving and a firm spring bar. A well-finished case on a thin, stiff strap is a warning sign about where else corners were cut.
Replica tiers compared
Budget tier
Pros: lowest cost, often visually acceptable at arm's length, easy to replace. Cons: quartz or basic automatic movement, solid caseback, printed subdials, wrong thickness. Best for a costume piece worn occasionally.
Mid tier, 7750 based
Pros: real automatic chronograph, closer case proportions, working subdials. Cons: thicker case, softer pusher feel, rotor and bridge decoration that does not match the genuine layout. Best for someone who wants a mechanical chronograph on a moderate budget and accepts the thickness penalty.
High tier
Pros: display caseback with decorated movement, correct 41 mm proportions, applied markers and better print, pushers that feel close to the real thing. Cons: highest cost, still not a genuine watch, and you need to verify the seller's photos carefully. Best for a buyer who wants the watch to hold up under close inspection.
Who should buy which
If the watch will be worn daily and seen up close by people who know watches, go high tier and insist on photos of the movement through the back. If it is a weekend piece and you mainly care about the dial, a mid tier automatic gives you a real chronograph without the price of the top tier. Skip the budget tier if a display caseback matters to you, because that is exactly the feature it cannot deliver.