Top pick: a fake IW371643 that gets three things right before anything else, the 41 mm case with its thin bezel and short lugs, the vertical bicompax dial with running seconds at 6 and the 30 minute counter at 12, and flat applied numerals under a domed sapphire. Everything below is the checklist I run against a listing, ordered by how much each item changes the watch on the wrist. The genuine reference is an IWC Portugieser Chronograph, so pull the exact case, dial, and calibre spec for IW371643 from IWC's own reference data first and treat that as your benchmark.
Case size and profile
The Portugieser Chronograph lives or dies on proportion. A 41 mm case that measures close to 13 mm thick with a narrow bezel reads correct on a 6.5 to 7.5 inch wrist. A copy that adds a millimeter of thickness or widens the bezel looks like a different watch in photos and worse in person.
Fake IW371643 Synonyms: The Words Buyers and Sellers Actually Use
- Pros: correct lug curvature and caseback depth sit flush on the wrist, crown and pushers line up with the caseband, and the watch photographs like the real thing.
- Cons: thicker cases push the strap out at the lugs, polished flanks show machining lines under raking light, and oversized crowns catch on cuffs.
Use case: this is the first filter for anyone buying from photos alone. If the thickness and bezel width are wrong, stop there and look at another listing.
Dial layout and subdial placement
The IW3716 family uses a vertical layout, not the horizontal tri-compax found on most chronographs. Running seconds sit at 6, the chronograph minute counter sits at 12, and the date window, where fitted, sits at 3. Subdial spacing on a bad copy drifts toward the center or the edges.
- Pros: correct spacing keeps the dial balanced, a proper railway minute track frames the layout, and subdial hands reach the right markers.
- Cons: subdials that are printed rather than recessed look flat, and some copies add a date window to a reference that never had one.
Use case: best for buyers who spend time looking at the dial rather than the movement. This is the criterion that decides whether the watch reads as a Portugieser at arm's length.
Chronograph action and movement feel
The modern reference runs an in-house column wheel chronograph, and the earlier version used a modified Valjoux 7750. That difference shows up in the pusher feel. A column wheel start is light and crisp; a 7750 has a firmer push and a rotor that spins visibly when you flick your wrist.
- Pros: crisp pusher engagement, a seconds hand that snaps back to zero on reset, and a smooth sweep at the right beat rate.
- Cons: gritty pushers, a reset that hesitates, and rotor noise that is louder than the real movement.
Use case: suited to buyers who will actually use the chronograph. If you never touch the pushers, spend your attention on the dial instead.
Printing, hands, and applied markers
Leaf shaped hands, applied Arabic numerals at 12 and 6, applied baton markers elsewhere, and fine text. Under a loupe, the tell is the edge quality of the printing and whether the markers sit flat or tilt.
- Pros: clean serif text, markers flush with the dial, and hands with a proper curve rather than flat stamped metal.
- Cons: thick printing that bleeds at the edges, markers glued at an angle, and hands that are too short to reach the track.
Use case: good for buyers who photograph their watches. Printing flaws are the first thing a macro shot exposes.
Caseback, engraving, and serials
A display back should show a decorated movement with a rotor and bridges that look finished, not sandblasted. Reference and serial engravings should be crisp and consistent in depth.
- Pros: sharp laser etching, correct reference formatting, and a sapphire window with the right tint.
- Cons: shallow engraving you can feel with a fingernail, mismatched fonts, and movements that are plainly unfinished.
Use case: relevant if you plan to show the back or resell later. It is the last thing to check, not the first.
Seller checks and the legal line
Ask for dated, in-hand photos with the chronograph running, confirm the return window in writing, and pay with a method that can be reversed. Be clear on the law: counterfeits are subject to seizure by U.S. Customs and Border Protection at import, and selling them carries civil and criminal exposure under trademark law.
- Pros: written return terms and real photos remove most of the risk from a remote purchase.
- Cons: stock images, pressure to pay off-platform, and no stated return policy are all reasons to walk away.
Use case: essential for first-time buyers. A seller who will not send fresh photos is telling you what the watch looks like.