The fastest way to identify a fake IW371628 is to inspect the movement, the dial printing, and the caseback engraving, in that order. Genuine IWC Portugieser Chronographs use a Swiss chronograph movement with a distinct pusher feel and clean finishing under a sapphire display back, and counterfeit versions nearly always expose themselves at one of those three points. If any check fails, treat the watch as not genuine and walk away.

What the IW371628 Reference Is

IW371628 belongs to the IWC Portugieser Chronograph line, a family of references that share one design language: a large, open dial, two subdials, applied numerals, and a slim bezel. IWC has released many references in this line with different dial colors, case metals, and strap options, so no single photo represents every IW371628. Before you judge a watch, pull the exact reference specs from IWC's official product data and compare them with the piece in front of you. Counterfeiters depend on buyers who only know the general look of the model.

Check the Movement First

The movement is where replicas struggle most, and on this reference it is often visible through the caseback.

• Look at the rotor engraving. Genuine engraving is sharp, evenly filled, and consistent with the calibre number that matches the reference.
• Check the finish of bridges and plates. Real perlage, Geneva stripes, and blued screws sit under a clear sapphire crystal. Copies show shallow, cloudy decoration.
• Test the pushers. A genuine chronograph starts and resets with a firm, short travel. Mushy or grinding pushers point to a cheap module.
• Feel the winding. A Swiss automatic winds with steady resistance and almost no noise. A low-grade copy feels gritty or slips.

Compare the calibre visible in the watch with the calibre IWC lists for your reference. Genuine 3716 references were produced with more than one movement over the years, so the correct calibre depends on the specific reference and production period. A mismatch is a red flag.

Dial, Printing, and Subdials

• Printing: genuine text sits crisp and level under magnification. Fake dials show thick, bleeding, or slightly crooked letters.
• Applied numerals: solid metal with polished edges, no glue residue, no misalignment, and correct spacing around the subdials.
• Subdial rings: even spacing, no doubled lines, and hands that reach the correct marks.
• Date window: cut square and clean, with an aligned disc and no gaps at the edges.
• Hands: correct length and shape, consistent brushing direction, and even lume application if the reference has it.

Case, Crown, and Pushers

Case finishing separates good replicas from poor ones. Run a fingernail along the transition between brushed and polished surfaces. On a genuine case the change is a defined line, not a soft blur. Crowns should thread smoothly, sit flush against the case, and carry a correct logo. Pushers should be level in height and centered in their tubes. Check the crystal as well. Genuine sapphire shows a faint blue or purple tint at an angle and resists scratching, while mineral glass on copies scratches early and reflects light differently.

Caseback Engravings and Serial Numbers

• Reference and serial numbers should be crisp, evenly spaced, and consistent with each other.
• Compare the serial against known production ranges for the reference. Numbers outside those ranges are a warning sign.
• Deep, laser-soft, or uneven engraving is common on fakes.
• Model names should match the reference exactly, including spelling and any accent marks.

Serial number checks are not proof on their own. Counterfeiters copy real numbers, so a number that looks valid only confirms the watch matches a genuine one on paper, not that the case and movement are real.

Strap, Buckle, and Packaging

Stitching, leather grain, and hardware weight are useful clues. A genuine alligator or calf strap has tight, uniform stitching and a buckle with correct hallmarks and logo depth. Packaging is the weakest check of all, because boxes and papers are copied in volume. Treat a full set as supporting evidence, not as proof. A watch with perfect papers and a suspicious dial is still a fake.

Price and Paperwork Reality Check

Genuine IWC Portugieser Chronographs hold value on the secondary market, and a price far below the going rate for the reference is the most reliable single warning sign. Sellers who push urgency, refuse to show the movement, or send only stock photos are a risk regardless of the reference. Ask for dated photos of the caseback, movement, and serial, and pay through a channel that offers buyer protection.

Get It Verified Before You Pay

An IWC boutique or authorized service center can confirm authenticity and service history. Independent watchmakers who service Swiss chronographs can also open the case and check the movement. For online purchases, an escrow or authentication service adds a layer of protection. If a seller refuses an inspection, that refusal answers the question for you.