Quick Answer

A fake IW371416 gives itself away in four places: the dial layout and the missing date window, the case measurements, the depth and alignment of the caseback engraving, and the movement behind the solid back. The genuine reference is a 40.9 mm stainless steel Portuguese Chronograph with a two-register dial, no date, sapphire crystal, and an IWC caliber 79350 inside. Any example with a date aperture, a three-register dial, or a glass caseback sold as a stock IW371416 is not the watch it claims to be.

Before You Start

  • A 10x jeweler's loupe
  • Digital calipers or a steel ruler
  • A timing machine, or access to a watchmaker who owns one
  • Seller photos of the dial, caseback, and movement, plus box and papers
  • A current dealer listing for the same reference as a price baseline

Step by Step

  1. Measure the case with calipers. A genuine IW371416 measures 40.9 mm across the bezel and about 12.3 mm thick, with 20 mm lugs. Copies often land at 41.5 mm or 42 mm and sit taller because the case is built around a stock movement and a spacer ring.
  2. Count the subdials and look for a date. The 3714 dial is a bicompax layout: chronograph minutes at 12 and running seconds at 6. There is no date window at 3 o'clock. A date aperture on a dial presented as an IW371416 is a copy, because the reference was never built with one. Some fakes add a third subdial or a 24-hour indicator as well.
  3. Read the dial printing through the loupe. Genuine dials carry the IWC mark with SCHAFFHAUSEN beneath it, printed sharp and level. Fakes show ragged edges, uneven letter spacing, grayish ink, and applied numerals that sit too thick off the dial or show adhesive at the base.
  4. Check the hands and the subdial hands. The main hands are leaf shaped, thin at the tip, with a clean polished bevel. Press the chronograph reset and watch where the minute counter lands. Both subdial hands should snap back to zero and stay there. Fakes drift or overshoot.
  5. Tilt the crystal under a light. Sapphire with anti-reflective coating shows a faint blue or violet sheen at an angle and a slightly domed profile. Mineral glass copies show a flat greenish reflection and pick up surface scratches.
  6. Turn the watch over and study the caseback. It should be solid steel with deep, crisp engraving: the IWC mark, International Watch Co., Schaffhausen, the reference number, the serial number, and the water resistance rating. Shallow laser etching, a mismatched font, or a serial that does not match the papers points to a copy.
  7. Note the caseback type itself. A stock IW371416 has a closed back. If a seller shows an exhibition back with a decorated rotor and calls it the same reference, treat the offer as a replica or a modified watch.
  8. Ask the seller for the full set: box, warranty card, booklet, and original invoice. Compare the reference and serial on the card with the engraving on the caseback. Request service receipts from an IWC service center if any exist.
  9. Have a watchmaker open the back. The correct movement is the IWC caliber 79350, a Valjoux 7750 base with a 28,800 vph beat rate and around 44 hours of power reserve. Look for perlage or Geneva stripes, polished screw heads, and a rotor marked with the IWC name. A bare, unmarked chronograph movement or a quartz module settles the question.
  10. Put the watch on a timing machine. A healthy 79350 shows a rate within about plus or minus 10 seconds per day, strong amplitude, and low beat error. A cheap chronograph module often produces an erratic trace and weak amplitude.
  11. Compare the asking price with current dealer listings for the same reference in similar condition with box and papers. A price far below market, or a seller who refuses escrow and inspection, is a warning sign.
  12. Pay for an independent authentication before you transfer money. A watchmaker or an auction house specialist can confirm the movement and the case in hand.

Red Flags

  • A date window or three-register dial on a watch sold as a 3714
  • A case measuring 41.5 mm or larger
  • A glass caseback on a stock reference
  • Shallow laser engraving on the caseback, or a serial that does not match the card
  • Mineral glass instead of sapphire
  • Mushy pushers, or a reset that does not return to zero
  • No box, no papers, no service history, and a price below market

What a Visual Check Cannot Prove

Well-made replicas copy the dial layout, the case size, and the engraving closely enough to survive a photo review. The movement is the part that is hardest to fake at cost, so caseback removal and a timing check remain the decisive tests. Buy from a dealer who allows inspection, or budget for a watchmaker's fee as part of the purchase.