Quick answer
The replica IW376045 copies the IWC Aquatimer Chronograph, a steel dive watch with a 44 mm case, an automatic chronograph movement, an internal rotating dive bezel and a day-and-date window at 3 o'clock. A good copy matches the 44 mm case width, the 22 mm lug spacing, the subdial positions at 12, 6 and 9, and the flat sapphire crystal with inner anti-reflective coating. Most flaws show up in four places: the bezel grip, the pusher feel, the date font and the caseback engraving.
Prerequisites
- A caliper or a steel ruler
- Reference photos of the genuine reference from IWC or an auction listing
- Daylight, a loupe or a phone macro lens, and a small flat screwdriver for strap changes
- A kitchen scale that reads in grams
Know the genuine reference first
The IW376045 belongs to the IWC Aquatimer Chronograph family. The genuine watch runs about 44 mm across, roughly 15 mm thick, with 22 mm lugs. It uses the IWC calibre 79320, an automatic chronograph built on the Valjoux 7750 architecture, with a 44 hour power reserve and a day-date display. Water resistance is rated to 300 m and the crystal is sapphire with an inner anti-reflective coating. Because IWC shipped several dial and bezel variants in this family, confirm the exact dimensions for your target reference before you compare anything.
How to inspect a replica IW376045
- Measure the case across the 9 and 3 o'clock line with the crown excluded, then measure the thickness from caseback to crystal. Expect close to 44 mm and about 15 mm.
- Measure the lug width. It should read 22 mm, and the spring bars should sit flush in the lugs without rattle.
- Count the subdials. A correct layout has running seconds, a 30 minute chronograph counter and a 12 hour counter, with the day-date window at 3.
- Study the date and day fonts under a loupe. Print should be crisp and centered, not fat or smeared, and the day should be spelled in full.
- Turn the internal bezel through its full rotation. It should move in firm steps with no back play and the lume pip should line up exactly at 12.
- Press each chronograph pusher. Start, stop and reset should each give a clean click, and the reset hand should snap back to zero without drifting.
- Hold the watch to your ear and rotate it. The rotor should spin without grinding or scraping the caseback.
- Inspect the caseback engraving with a loupe. Reference numbers, the IWC wordmark and the depth rating should be cut into the metal, not stamped flat or laser printed.
- Tilt the crystal under a lamp. The inner anti-reflective coating should kill most reflections, leaving a faint blue or purple tint at steep angles.
- Weigh the watch on a head. A steel case with a steel bracelet should land in a plausible range for the genuine piece, not feather light.
- Set the time, wind it 40 turns and let it run for 24 hours face up, then log the gain or loss against a phone clock.
What each price tier buys
Budget copies use a generic 7750 clone with a stamped date wheel and a printed caseback. Mid tier copies add a decorated rotor, a proper day-date disc and a machined bezel. The top tier copies use a Swiss or high grade Asian 7750, sapphire on both sides and case dimensions that hold within a fraction of a millimeter. If a listing claims Swiss movement at a budget price, treat the claim as false.
Red flags
- Case width off by more than 0.5 mm
- Date window with a magnifier that the genuine reference does not have
- Bezel that spins freely instead of clicking
- Chronograph seconds hand that rests left or right of 12 after reset
- Seller photos that avoid the caseback, the crown side and the clasp
After you buy
Have a watchmaker pressure test the case before any water contact, since factory seals on copies are unreliable. Keep the bracelet screws tight and rinse the case with fresh water after salt exposure. A service every three to five years keeps the chronograph module running clean.