Short answer
A fake IW327012 misses on three parts: the movement, the caseback engraving, and the crystal. A genuine IWC Mark XVIII runs caliber 35111 at 4 Hz with a 42-hour power reserve. Copies carry a lower grade automatic with a printed or stamped rotor. Caseback text on a copy sits shallow and uses fonts that drift from IWC's. Genuine sapphire has anti-reflective coating on both faces, which shows a blue tint at an angle. Most copies coat one face or none. No external check confirms a watch on its own. A watchmaker or IWC service has to open the case.
The reference
IW327012 sits in the IWC Pilot's Watch Mark XVIII family. The case is stainless steel, 40 mm across the bezel. Lug width is 20 mm. Water resistance is 6 bar. The caseback is solid steel, not a display back. IWC built several Mark XVIII references that share this case and differ in dial color and strap. Confirm the dial and strap combination for IW327012 in IWC's records before you judge a watch.
Movement
Caliber 35111. Base is the Sellita SW300-1. Power reserve is 42 hours. Beat rate is 28,800 vph. A copy often uses a movement from a different family, and the rotor engraving is the tell. Some copies print a caliber number on a rotor that belongs to another movement. A watchmaker can open the case and read the markings in minutes. The date should flip within a minute or two of midnight. Copies drift past that window.
Caseback and serial
Genuine engraving carries the reference number, the serial number, the IWC name, Schaffhausen, and the model name. Lines are cut deep with consistent stroke width. Copies show shallow laser marks, uneven spacing, and letter shapes that do not match. A serial number alone does not prove authenticity. Confirm the watch through IWC service, an authorized dealer, or a watchmaker.
Dial, hands, and crown
Printing on a genuine dial stays crisp at 10x magnification. Applied indices sit flat with polished edges and an even fill of lume. The date disc lines up with the aperture and the numerals sit centered. The crown is signed, screws down, and stops with a firm seat. On copies the printing feathers, the lume sits uneven, and the crown threads feel rough or fail to seat.
Strap, buckle, and box
Some variants ship on Italian leather from Santoni. The buckle is signed. Boxes and papers are the easiest part to copy, so a full set proves little. A common flag is a card with a serial that does not match the caseback.
Checks before you buy
- Measure the case and lug width. Look for 40 mm and 20 mm.
- Tilt the crystal under a lamp. Look for a blue sheen on both faces.
- Inspect caseback engraving with a 10x loupe. Compare stroke depth and font.
- Check that the crown screws down and the date flips near midnight.
- Ask a watchmaker to open the case and read the movement and rotor.
- Compare the asking price against recent sold listings for a full set. A steep discount is a flag, not proof.
What no guide settles
A copy can pass every check above. Case dimensions, weight, and dial printing get close on the better copies. The movement and the service history are where the two part. If the seller blocks an inspection, walk away.