Short answer
IW371771 is an IWC reference number. IWC writes references as IW plus six digits. The number defines one case, dial, and strap combination inside a model family. Public IWC catalog pages for this exact number are not indexed in the sources checked here. Confirm the base model before you compare a replica against it.
What the number covers
One IWC family holds dozens of references. Two watches can share a case and differ by dial color, hands, or strap. Reference numbers let collectors match parts. Sellers use them to sound precise. Ask for the family name, the case diameter in millimeters, and the movement caliber. A seller who cannot name those three items is guessing.
Checklist before purchase
- Case diameter and thickness. Measure the watch, not the listing photo.
- Lug width. Many IWC chronographs use 20 mm or 21 mm.
- Subdial spacing. A 7750-based movement pushes subdials apart.
- Date window position and font weight.
- Crystal. Genuine pieces use sapphire with coating on both faces.
- Caseback engraving depth and letter spacing.
- Bracelet end link fit and clasp code.
Movement
Most replicas in this price band run a Sellita SW500 or a Chinese 7750 clone. Both are automatic chronographs with 25 jewels. Beat rate is 28,800 vibrations per hour. Power reserve is about 44 hours for the SW500 and less for the clone. Genuine IWC chronographs of this period use an in-house or modified 7750 base. Rotor shape and finish differ, and that shows through a display back.
Price bands
Replicas of this reference sell between $250 and $700, based on movement and finishing. Genuine examples on the secondary market sit far above that range. A $150 listing for a claimed high-grade replica points to a low-grade movement and a plated case.
What replicas miss
Case finishing, dial printing under a loupe, and movement decoration. Service access is another gap. Most replica movements cannot be serviced by an IWC-trained watchmaker, and parts are not interchangeable with the original.
Steps to verify a claim
- Get the full reference number and the family name.
- Compare case dimensions against published specifications.
- Request movement photos, including the balance and rotor.
- Ask about water resistance testing. Most replicas ship untested.