What a fake IW371651 is
A fake IW371651 is a replica of the IWC Portugieser Chronograph. It copies the 41 mm stainless steel case, the two-register dial layout, and the applied numerals. Quality ranges from obvious counterfeits with quartz movements to high-end replicas that use decorated automatic calibres. The reference number IW371651 points to a specific dial and strap combination in the Portugieser line. Knowing the genuine details helps you separate a poor fake from a close copy.
Prerequisites before you inspect
- A 10x jeweler's loupe
- Bright, diffused light (a desk lamp or window light)
- Reference photos of a genuine IW371651 from an authorized dealer or trusted listing
- Digital calipers for case thickness and lug width
- A quiet room to listen to the movement
How to inspect a fake IW371651 step by step
- Measure the case diameter and thickness with calipers. Genuine Portugieser Chronograph cases are 41 mm wide and about 13.1 mm thick. Many fakes are 1 to 2 mm thicker or wider.
- Check the subdial spacing at 12 and 6 o'clock. On the genuine watch, the two subdials sit close to the center and align with the hour markers. Fakes often have wider spacing or misaligned subdial rings.
- Examine the dial printing under a loupe. The IWC logo and "Portugieser" text should be crisp with no bleeding or rough edges. Fake printing looks fuzzy or uneven.
- Look at the date window. Genuine IW371651 models have a date aperture with a precise cut and a font that matches the dial. Replicas often use a generic date wheel with wrong font or misaligned numbers.
- Inspect the crown and pushers. The crown should have a sharp IWC logo and screw down with no grit. Pushers should have a firm click and no side play.
- Turn the watch over and read the caseback engraving. Genuine engraving is deep, sharp, and consistent. Fake engraving is shallow, blurry, or uses the wrong font.
- Listen to the movement. A genuine IWC calibre 69355 or 79350 runs with a soft hum and a smooth sweep. Fake movements, especially quartz or low-grade automatics, tick loud or have a rattling rotor.
Movement details that expose a fake
The genuine IW371651 uses an IWC in-house automatic chronograph movement. Earlier versions used a modified ETA/Valjoux 7750 base, while newer versions use the calibre 69355. A fake often hides a Chinese clone or a quartz movement behind a decorated plate. Look for a smooth sweep of the chronograph seconds hand. A quartz fake ticks once per second. An automatic fake may have a rotor that spins with play or a winding action that feels gritty.
Dial and case finishing checks
Genuine Portugieser Chronograph cases have a mix of polished and brushed surfaces. The brushing is fine and straight. The polishing is mirror-like with no waves. Fakes cut corners with uniform brushing or over-polished edges that round off the lugs. The dial on a genuine watch has applied numerals with sharp edges and a sunburst or matte finish that changes with light. Fake dials often look flat or have printed numerals instead of applied ones.
What a high-end replica gets right
A high-end fake IW371651 can match the case dimensions and dial layout. It may use a real automatic movement and sapphire crystal. But it still fails on small details: the movement finishing, the date font, the crown logo depth, and the caseback engraving. These are the points to check when you compare a replica to a genuine reference.
Final checks before you buy or judge
Always compare the watch to official IWC photos for the exact reference. Check the serial number against IWC's records if you can. If the price is far below market value for a stainless steel Portugieser Chronograph, treat it as a fake. No genuine IW371651 sells for a few hundred dollars.