The reference IW371789 sits in the IWC Portugieser Chronograph family. The 3717 series uses a 42 mm case and the IWC 79320 calibre. The dial carries two subdials: chronograph minutes at 12 o'clock and running seconds at 6 o'clock. A date window sits at 3 o'clock. The final digits of an IWC reference encode case metal, dial color and strap. IWC does not publish a public lookup for each suffix, so the exact build of IW371789 needs a catalogue or a boutique check. A seller who offers an IW371789 below the secondary market range is selling a replica or a counterfeit.
Specs of the real 3717
- Case: 42 mm stainless steel, sapphire crystal with anti-reflective coating on both faces.
- Movement: IWC calibre 79320, automatic, 25 jewels, 28,800 vibrations per hour, about 44 hours of power reserve.
- Dial: two subdials, applied markers, printed minute track, date at 3.
- Strap: alligator leather, steel pin buckle or deployant clasp by variant.
The 79320 uses a Valjoux 7750 base. IWC reworks the movement and regulates it in house.
Where replicas fail
Movement
Replica chronographs often use a stock 7750 clone or a cheaper Asian movement. Checks: rotor engraving depth and font, perlage and Geneva stripes on the bridges, and the shape of the regulator. Real 79320 movements show a signed rotor and clean finishing under a loupe.
Case and crystal
Replica cases run thicker than the 42 mm spec and the lugs show soft edges. The sapphire on a real 3717 has a blue tint from the double-sided anti-reflective coating. Replica crystals look clear or gray.
Dial and hands
Print on fakes sits heavy. Subdial rings are stamped rather than applied. Hand length, lume color and the date font differ from the IWC original.
Caseback and numbers
Real IW3717 watches carry a reference number and a unique serial. Counterfeit batches repeat one serial across units. Engraving on fakes is shallow and the font is wrong.
Checks to run before you pay
- Ask for a photo of the movement with the caseback removed.
- Compare the reference and serial against IWC service records.
- Measure case thickness and diameter.
- Check the anti-reflective tint on the crystal under daylight.
- Ask for the original box, papers and service history.
Legal notes for US buyers
US Customs and Border Protection can seize counterfeit watches at import. Trafficking in counterfeit goods carries criminal penalties under 18 U.S.C. 2320. Payment platforms and card networks also freeze accounts tied to counterfeit sales.