The short answer
A fake IW371770 is a copy of the IWC Portugieser Chronograph: a steel watch around 41 mm across, two stacked subdials at 12 and 6, a slim bezel, and a display back. Replicas of it come in three rough tiers, and the price gap between them is almost all movement and case finishing, not dial printing. If you take one thing from this guide, take this: on every Asian 7750 chronograph with running seconds at 6 o'clock, that little seconds hand is driven through a set of transfer gears, and that gear train is where cheap copies fail first.
What the real watch is
The Portugieser Chronograph is IWC's dressy two-register chrono. Earlier references in the IW3717 family ran a movement derived from the Valjoux 7750, reworked in Schaffhausen as the calibre 79320. Cam and lever, not column wheel. That matters for replicas because the 7750 is one of the most copied movements on earth, so a rep factory has a cheap, well-documented base to build on. The genuine case sits around 12 to 13 mm thick. The crystal carries anti-reflective coating on both faces, which makes the dial look like it has no glass over it at all from an angle.
The three tiers you will see
- Entry, under about $200. Usually a 7750 clone with the seconds-at-6 module, thicker case, flat printing, single-side AR, stamped buckle. It runs, but the chrono feels gritty.
- Mid, roughly $300 to $500. Better case profile closer to the genuine thickness, applied numerals with decent polish, correct feuille hands, two-sided AR, sapphire back with some decoration on the rotor and bridges.
- Top, $600 and up. Correct subdial spacing, crisp lacquer or sunburst dial, sharp rehaut, engraved caseback lettering deep enough to survive a fingernail, and a properly serviced 7750 with the transfer gears cleaned and lubricated.
What I look at on the dial and case
- Subdial position. If the two registers sit too far apart or too close to the center, the case is a generic one, not cut for this reference.
- Printing weight. The brand text and the country line under 12 should be thin and even. Blobby ink is the fastest tell in photos.
- Hand shape. Feuille hands taper to a fine point. Rep hands often come blunt or slightly too wide.
- Crystal reflection. Double AR makes the dial pop. Single AR leaves a blue or green haze.
- Case thickness. Anything over 14 mm is a give-away from across a table.
- Caseback engraving. Look for crisp depth and correct reference text, not laser-etched grey lines.
- Strap. Genuine-grade alligator is rare at this price. Most copies ship embossed calf that creases within weeks.
Movement: where the money actually goes
Ask for a movement photo before you buy. A decorated Asian 7750 should show Geneva striping on the rotor, blued screws that are blued rather than painted, and a balance that swings freely when you tilt the watch. Wind it slowly and listen. A dry, rasping sound means the transfer gears are running unlubricated, and the seconds hand will start stuttering within months. The chrono pushers should start, stop and reset with a firm click, and the reset should snap both hands back to zero at the same instant. If the chrono second hand lands one tick off zero, walk away.
Red flags
Sellers who will not show a movement shot, prices far below the tier they claim, stock photos lifted from a boutique listing, and any promise of brand servicing. A replica cannot go to an authorized service center, and no seller can arrange that. Treat any claim of "same factory as the genuine" as noise.
One honest note
This is a copy of a $8,000 watch. It is not the watch, it will not hold value, and it should never be sold or represented as genuine. Buy it because you like the look on your wrist, budget for a service in the first year, and keep it away from water regardless of what the listing says about depth ratings.