Quick answer
A replica IW371642 is a copy of the IWC Portugieser Chronograph built on the 3716 reference platform. Good copies match the 41 mm case, the two-register dial with running seconds at 6 and chronograph minutes at 12, and the date at 3. Weak copies run thick, add a third subdial where none belongs, or use a dial color that turns purple in daylight. Judge a copy on movement layout and case measurements first, then dial printing, then the strap.
What the original reference is
IW371642 sits in the current 41 mm Portugieser Chronograph generation. Every reference in that family shares one case, crystal, and dial architecture. The suffix only changes dial color, hand finish, and whether the watch ships on a leather strap or a steel bracelet, so confirm which combination the listing claims to copy.
- Case: stainless steel, 41.1 mm wide, about 13.1 mm thick
- Dial: two registers, small seconds at 6, chronograph minutes at 12, date at 3
- Movement: IWC calibre 69355, automatic, 28,800 vph, 46-hour power reserve, column wheel
- Crystal: sapphire with anti-reflective coating on both faces
- Lug width: 20 mm, with either an alligator strap or a steel bracelet
One detail matters for buyers. The 69355 sits on a 7750-derived architecture, which is why so many copies use 7750 parts, and why the dial layout tells you more about a copy than the name printed on its movement.
Where copies usually differ
Movement and subdial layout
A stock 7750 carries subdials at 12, 6, and 9. The Portugieser carries two, at 12 and 6. A copy that shows a small third counter at 9, or a blanked circle there, is running an unmodified movement behind a dial with a filler. Ask for a straight-on dial photo and count the registers.
Case and thickness
Thin is hard to fake. Many copies land between 14 and 15 mm because the movement and its spacer add height. Put the case on calipers if you can, or compare a side profile shot against the 13.1 mm figure. Check the lug profile as well. The original tapers with a light curve, while copies often cut lugs thicker and flatter.
Dial and printing
Read the dial from top to bottom. You want a sharp IWC wordmark, Schaffhausen below it, and Automatic and Chronograph set at the correct height. Sloppy copies smear the fine text, crowd the subdial rings, or print the date window off center. Hold a blue or green dial at an angle in daylight. A gray or purple undertone means the sunburst finish is wrong.
Crystal, crown, and strap
The sapphire should sit nearly invisible with a faint blue or purple reflection from the inner coating. Heavy tint or a milky edge points to a cheap crystal. The crown should carry the Probus Scafusia engraving and wind without grit. Straps range from stamped leather on a folded buckle to real alligator on a signed deployment clasp.
How to check a replica IW371642 before you buy
- Ask the seller for the exact suffix and the dial and strap combination shown.
- Request a straight-on dial photo and count the registers: two, at 12 and 6.
- Request a side profile and estimate case thickness against 13.1 mm.
- Zoom on the date window at 3 and check font, size, and alignment.
- Zoom on the wordmark and count the printed lines on the dial.
- Press the chronograph start, stop, and reset and listen for a clean click.
- Run the chronograph, reset it, and confirm the hand returns to zero.
- Turn the watch over and read the caseback engraving depth and rotor finish.
- Tilt the crystal under a lamp and check for tint and internal reflection.
- Inspect the strap and clasp, then decide if the price fits the tier you see.
Questions to send the seller
- Which movement is inside, and does the 30-minute totalizer work?
- What is the measured case thickness with the caseback on?
- Does the date change over cleanly at midnight, or creep from 10 p.m.?
- Is the strap genuine leather, alligator, or synthetic?
- What power reserve do you get overnight, and does the rotor spin freely?
What to expect after delivery
Set the time, wind it 30 turns, and let it sit for a day to check the rate. Wear it for a week before judging comfort, since the 20 mm lug width and 41 mm case suit most wrists between 6.5 and 7.5 inches. A chronograph copy that resets to zero and holds within 20 seconds a day is doing its job.
Care notes
Keep the watch away from strong magnets, since the 7750 family is sensitive to them. Rinse the case and bracelet with fresh water after sweaty wear, and dry the strap before storing it. Have the movement cleaned every three to five years if you use the chronograph often, and skip the pool unless the seller states a tested water resistance rating.