A fake IW371748 almost always gives itself away on four points: case thickness, the day-date aperture, the movement's beat rate, and how the pushers feel. Start there. The genuine IWC Pilot's Watch Chronograph in the IW3717 family runs a 42 mm case, a modified Valjoux 7750 (calibre 79320) at 28,800 vph, and a combined day-date window at 3 o'clock. Copies match the footprint and miss everything else.

What the IW371748 Should Be

The reference belongs to the IW3717 series, IWC's larger pilot chronograph produced through the 2000s and early 2010s. Expect a stainless steel case around 42 mm wide and roughly 14.5 to 15 mm thick, a soft-iron inner cage for magnetic protection, a screw-in caseback, and a domed sapphire crystal with anti-reflective coating on both faces. The dial carries a 12-hour chronograph totalizer at 12, running seconds at 6, and permanent seconds at 9. Day and date share one window at 3.

Step-by-Step Authentication

  1. Measure the case with calipers, crown excluded. Anything below 41.5 mm or above 42.5 mm is wrong. Copies often shrink the case to reuse a smaller generic blank.
  2. Measure the thickness at the caseback rim. A genuine example sits between 14.5 mm and 15.2 mm. Many fakes come in under 13 mm because they use a thin quartz or low-grade automatic movement.
  3. Time the running seconds against a reference clock. Count beats in fifteen seconds. A genuine calibre 79320 ticks eight times per second, so you should count 120 beats per minute. A 21,600 vph copy will show 90.
  4. Study the day-date window. Genuine apertures sit slightly recessed with crisp beveled edges, and the day disc aligns with the date disc. Fakes show a flat cut-out, misaligned printing, or a date wheel that jumps late.
  5. Press the pushers and reset the chronograph. Genuine pushers travel with firm resistance and the reset snaps the hands to zero in one motion. Cheap copies feel spongy and creep back.
  6. Read the caseback engraving under a loupe. Reference numbers, the serial, and the IWC script should be crisp and evenly cut. Laser-etched or shallow stamped text is a sign of a copy.
  7. Weigh the watch head on a kitchen scale. A genuine steel IW3717 head sits near 100 grams. Lightweight heads point to a plated base metal case.
  8. Check the lume under a UV light. Genuine Super-LumiNova glows evenly for hours. Fake lume glows bright for a minute and fades to nothing.
  9. Look up the serial with IWC or an authorized dealer. A real serial returns a matching reference and production window. Reused or missing serials end the conversation.

Dial and Hand Details

The applied numerals on a genuine IW3717 are polished and sit proud of the dial, with sharp inner angles. Fake numerals look flat, thick, or slightly brown at the edges. Hands on the original are faceted and coated, so the centers catch light in a straight line from base to tip. Copies use stamped hands with rounded edges and uneven lume fill.

Subdial printing is the second tell. Genuine text is thin, sharply defined, and consistent in weight across all three registers. Copies blur the smallest lines or use a heavier font that bleeds into the track.

Movement and Caseback Checks

The caseback is a screw-in design with a soft-iron shield behind it. Once opened, the calibre 79320 shows Geneva stripes, a signed oscillating weight, and a shock-absorbing balance assembly. Fake movements typically show a plain rotor, no perlage, and a plastic movement ring. If the seller refuses to open the case, walk away.

Papers, Box, and Serial Records

Genuine sets include a warranty card with the serial, a matching reference, and an IWC booklet printed on heavy stock. Fakes ship with cards where the serial does not match the caseback stamp. Always compare the two numbers side by side under light.

Red Flags That End the Deal

  • The seller quotes a price far below the current market for the reference.
  • The watch is offered with no serial number or a polished-off caseback.
  • Photos are stock images or show a different reference than the listing title.
  • The seller refuses a third-party authentication or an escrow payment.
  • The crown screws down in fewer than two turns.
  • The chronograph second hand stutters instead of sweeping.