A fake IW371756 gives itself away in four places: the case back engraving, the movement under the case back, the dial text and index finishing, and the serial number. Check them in that order. Most replicas fail the first two within ten minutes, and the good ones fail the third.
What You Need Before You Start
- A 10x loupe or a phone macro lens
- Digital calipers and a kitchen scale accurate to 0.1 g
- Reference photos of the genuine IW371756 from IWC's own archive page
- Bright daylight or a 5000K lamp
- A local watchmaker willing to open the case back for a small fee
Step-by-Step Checks
- Measure the case diameter and thickness with calipers and compare both numbers to the published specification for IW371756. Replica cases usually run 0.3 to 0.8 mm thicker because the movement sits in a spacer ring.
- Weigh the watch head on its own. Treat weight as a supporting signal, not proof. Plated brass cases read light, but a well-built replica can land within a few grams of the real thing.
- Study the case back engraving under the loupe. Genuine IWC engraving has crisp walls and a matte, sandblasted field. Replicas show rounded edges, shallow depth, and lettering that thickens where the laser stalled.
- Check the reference and serial number font. Compare the numerals against IWC's own photograph, digit by digit. Replica engravers often swap a 7 for a 1 or space the characters wrong.
- Have the watchmaker open the case back. Photograph the movement through the loupe and compare rotor engraving, perlage, and bridge bevels with reference photos.
- Look at the dial under 10x. Genuine applied indices sit flat, reflect light in one clean plane, and show no glue. Replica indices tilt, wobble, or show a glue halo at the base.
- Read the dial text at arm's length, then under magnification. Replica printing uses a different weight and often a different typeface for the brand name and the reference line.
- Run the chronograph. Start, stop, and reset the seconds hand several times, then check that it returns exactly to twelve. Slow or drifting reset points to a cheap chronograph module.
- Cycle the crown through all positions. Genuine crown action is firm and clicks once per position. Replica crowns feel gritty or spin past a position.
- Charge the lume with a torch for ten seconds and watch it fade in a dark room. Replica lume dims within minutes and often glows a different tint.
- Send the reference and serial number to IWC customer service or an authorized dealer and ask them to confirm the configuration. This step settles the question.
Red Flags That End the Inspection
- Serial number repeated across two watches for sale at the same time
- Case back screws that sit proud of the case or show stripped heads
- Dial printing that smears when you breathe on it
- A bracelet clasp with uneven engraving or a loose push-button
- Seller who refuses an in-person inspection by a watchmaker
Replica Tiers and What They Miss
Cheap quartz replicas fail at the dial and the case back. Mid-tier automatic replicas pass a glance and fail a loupe. The best replicas copy the case profile and dial layout well, then lose on movement finishing and engraving depth, because those steps cost real machining time. If you are buying a replica as a replica, buy it knowing that. If you are buying secondhand and the seller calls it genuine, every one of the checks above is a reason to walk away.
Common Mistakes
- Judging from a seller's photos instead of the watch in hand
- Trusting box and papers, which are the easiest parts to copy
- Comparing against a different dial variant of the same reference
- Skipping the movement check because the case back looks right