Best Fake IW371643: The Short Answer
The best fake IW371643 is the build that matches the genuine Portugieser Chronograph on the parts you can measure: case diameter and thickness, subdial positions, date placement, hand shape, and chronograph behavior. It also comes from a seller who will send macro photos and accept returns. Price alone tells you nothing. Two sellers can list the same factory build at very different prices, and two factories can ship the same exterior with very different movements inside.
Prerequisites
- Reference photos of the genuine IW371643: dial, caseback, crown side, and lug profile
- A caliper or a steel ruler marked in millimeters
- A jeweler's loupe (10x) or a phone macro lens
- The seller's written return window and refund terms
How to Check a Replica IW371643 Step by Step
Confirm the reference before you compare anything. Ask the seller for the exact model code and dial variant, then pull IWC's own catalog page for that 3716 variant and note the published case size, dial color, and strap options. Compare like with like, because the 3716 family spans several dial and bracelet versions.
Measure the case. Check diameter across the bezel at 3 to 9 o'clock and thickness at the caseback crown. A build that runs 1mm or more off the published figure will sit wrong on the wrist and will not take a genuine-spec strap cleanly.
Map the dial layout. The running small seconds sits at 6 o'clock, the 30-minute chronograph counter at 12, and the date window at roughly 4:30 on this reference. Subdials that are glued on rather than recessed, or that sit a millimeter off center, are the fastest giveaway.
Inspect the printing under magnification. Brand text and the model line should be crisp with no ink bleed, no double edges, and no fuzzy serifs. Applied indices should sit flat and level, with no gaps under the feet.
Run the chronograph. Start it, let it run, and reset. The central seconds hand must sweep smoothly, the counter at 12 must advance, and the reset must snap back to zero without a wobble or a lag.
Listen to the movement. Hold it near your ear and start the chrono. A clean, even beat with no grinding or rattle points to a properly finished automatic chronograph caliber. Ask which movement is inside and whether it is a modified 7750 base or a clone of the in-house caliber.
Check the case finishing. Flanks should be brushed in one direction with even grain, bevels polished, and lug edges sharp rather than rounded off. Run a fingernail along the lug tops; soft, wavy edges mean a low-tier case.
Look at the crystal. The genuine watch uses a box-shaped sapphire with anti-reflective coating. Reflections should be faint and slightly blue on the edges, and the dial should stay readable at an angle.
Read the caseback engraving. Lettering depth, font weight, and spacing should match your reference photos. Shallow laser etching with thin outlines is a budget sign.
Verify condition on arrival inside the return window. Photograph the watch as you unpack it, time it for 24 hours against a reference clock, and confirm the chronograph still resets clean. Return it if anything from steps 2 through 9 fails.
Red Flags in Listings
- Stock catalog images only, with no macro shots of the actual unit
- Refusal to send a short video of the chronograph running and resetting
- "1:1" or "mirror quality" claims with no measurements or movement name
- Prices far below the going rate for the tier, which usually means a downgraded movement
- No written return policy, or payment by irreversible methods only
Legal and Practical Notes
Counterfeit watches infringe trademarks, and trafficking in them is illegal in the United States under 18 U.S.C. § 2320. U.S. Customs and Border Protection can seize counterfeit goods at the border, including personal imports, so an order can be lost with no refund. Selling a replica is a criminal risk; buying one is a financial and legal risk that sits entirely with you. Service is the other practical catch: an independent watchmaker may refuse to work on a counterfeit, and parts for clone movements are not always available.