The top pick for a fake IW371745 is a 1:1-grade steel build with a working chronograph, a dial that follows the genuine Portugieser Chronograph layout, and bracelet hardware that tapers and clasps the way the original does. Four criteria decide the outcome: case silhouette, dial printing and furniture, chronograph behavior, and strap or bracelet fit. This guide answers the question first, then walks through each criterion so you can grade a listing before you pay.
What a fake IW371745 actually is
Sellers use the phrase for three different products. The first is a quartz copy that reads as the reference from across a room and falls apart in the hand. The second is a mid-tier automatic with a generic chronograph movement, a case that is close but not exact, and a dial printed from a low-resolution file. The third is a 1:1 build: a custom case machined to the reference profile, a dial with applied numerals and correct subdial spacing, and a modified automatic chronograph movement with the pushers engaging in the right order.
The reference sits inside IWC's Portugieser Chronograph family, which spans several dial and bracelet combinations. Confirm the exact case size, calibre, and dial variant tied to IW371745 against IWC's own product listing before you compare a replica to anything, because the family shares a layout that is easy to blur: two subdials on the vertical axis, small seconds at the bottom, a 30-minute counter at the top, a date aperture on the right, leaf hands, and a slim bezel that leaves the dial open.
Criterion 1: case silhouette, thickness, and crown position
Case geometry is the fastest way to separate tiers. A correct case has lugs that curve down with a consistent radius, pushers that sit level with the crown, and a profile that stays slim when viewed from the side. Ask for a side photo next to a ruler rather than a straight-on shot, since every listing looks good straight on.
Pros of a corrected case
- Wears like the reference on the wrist, which matters more than any dial detail
- Accepts the original bracelet end links and aftermarket straps without gaps
- Photographs honestly, so you can spot problems before delivery
Cons
- Raises the price of the build, often by a wide margin over mid-tier copies
- Bezel and case-back engraving still differ from the genuine article on close inspection
- Polishing quality varies between batches from the same workshop
Recommendation: choose a corrected case if you plan to wear the watch daily and want the bracelet to sit flush. If the watch is a display piece for a collection shelf, a mid-tier case is acceptable.
Criterion 2: dial printing and applied furniture
Look at three places. First, the subdial rings: they should be crisp and evenly spaced, not fuzzy. Second, the numerals: applied metal markers with sharp edges and a polish that catches light along the top face. Third, the date window: cut clean, framed if the reference frames it, with a date disc that sits close to the dial surface.
Pros of a well-finished dial
- Carries the watch at arm's length, where most people actually see it
- Correct subdial spacing keeps the chronograph hands centered through a full run
- Text weight and font shape match the family layout
Cons
- Print quality is the hardest thing to check from seller photos, which are often over-lit
- Some builds use a flat disc instead of an applied marker and hope buyers miss it
- Dial swaps between batches mean two copies of the same listing can differ
Recommendation: request a macro photo of the 12 o'clock area and the date window in natural light. If the seller refuses, move on.
Criterion 3: chronograph function and movement behavior
The genuine reference uses an in-house IWC chronograph calibre, so a replica will never match the movement architecture. What you can check is behavior. Start the chronograph and watch the sweep: a smooth, steady central hand with no stutter and a clean reset to zero on both counters. Pushers should click once and engage, not grind.
Pros of a working automatic chronograph
- Adds a real function you can use instead of a decorative pusher
- Rotor winding gives an automatic feel on the wrist
- Holds up to daily wear better than a quartz module
Cons
- Costs more and needs servicing like any mechanical chronograph
- Rotor noise and beat rate differ from the genuine calibre
- Display case backs reveal the difference to anyone who knows movements
Recommendation: buy the automatic version if you use the chronograph. If you never press the pushers, a quartz build saves money without hurting the look.
Criterion 4: bracelet, clasp, and strap hardware
End link fit is the tell. On a correct build, the links meet the lugs with no step, the taper runs from the case down to the clasp, and the clasp closes with a firm single action. Screws should take a real driver and hold torque.
Pros
- Removes the rattle that gives cheap copies away in a quiet room
- Correct taper keeps the watch balanced on the wrist
- Strap changes become easy when spring bar holes align
Cons
- OEM-grade bracelets are the most expensive single upgrade
- Clasp engraving is rarely exact on any replica
- Link screws can strip if the workshop used soft metal
Recommendation: pick a leather strap build for a dress look and a bracelet build for daily wear. Do not pay a premium for a bracelet you intend to remove.
Red flags that end the conversation
- Photos taken only from one angle, or with heavy glare across the dial
- A seller who cannot say whether the movement is quartz or automatic
- Promise of a genuine IWC box and papers with a replica watch
- No return window written into the terms
Which build suits which buyer
First-time buyers who want the Portugieser look for occasional wear should choose a mid-tier automatic with a clean dial and a leather strap. Daily wearers should step up to the 1:1 case and bracelet build, because case geometry and end link fit affect comfort every day. Collectors who compare details under a loupe should accept that no replica survives that test, and should buy for the wrist experience rather than the case back.