An IW371734 is an IWC Pilot's Watch Chronograph from the 3717 family. Copies come in three grades: quartz copies, low-beat mechanical copies, and copies built on a Valjoux 7750 clone. The last group is the hard one. The case, dial and hands can pass a hand check. The movement and the caseback do not.
What the real watch is
- Stainless steel case, about 42 mm across, about 14.5 mm thick
- Calibre 79320, automatic, Valjoux 7750 base
- 28,800 vibrations per hour, about 44 hours of power reserve
- Day and date window at 3 o'clock
- Running seconds at 9, 30-minute counter at 12, 12-hour counter at 6
- Soft-iron inner case for magnetic shielding
- Sapphire crystal, screw-in caseback, 6 bar water resistance
- Leather strap or steel bracelet, based on the variant
Four checks that settle it
- Center hand. On a 7750 the large center hand is the chronograph seconds hand. It sits at 12 until you press the top pusher. The watch runs its seconds in the subdial at 9. If the center hand sweeps all the time, the movement is not a 7750.
- Beat rate. 28,800 vph is 8 beats per second. A 21,600 vph movement at 6 beats per second is wrong. A quartz copy ticks once per second.
- Day and date. The real watch shows both in one window at 3. The day disc sits above the date disc. Cheap copies show date only, or the two discs sit out of line.
- Pusher feel. The 7750 pushers give a firm, short click. Copies feel soft or travel too far.
Dial and case details
- Numeral print. Real strokes are thin and even. Copy numerals are thicker or uneven at the corners.
- Lume. Real lume sits inside the printed line. Copy lume spills over the edge.
- Date aperture. The real cut has sharp, chamfered edges. Copy cuts look punched.
- Caseback. Reference number, serial number and the Probus Scafusia engraving. Copy engraving is shallow and the letters lose their shape.
Movement and paperwork
A watchmaker can open the caseback in minutes. Genuine 79320 movements carry the IWC calibre stamp under the balance and a signed rotor. IWC's service department can check a serial number against its records. Ask for service papers. Send the watch for a service quote before you pay.
Price signal
A genuine example trades for about $4,500 to $8,000 USD on the used market, based on condition, box and papers. A listing at $500 is not a genuine watch. No seller takes that loss on a real one. A price far under market is the fastest tell of all.
What the reference number does not tell you
IWC uses the last digits of a reference to mark dial, case and strap combinations. Two watches with close reference numbers can look different. Confirm the exact variant in photos before you compare details.