The replica IW371670 is a copy of the IWC Portugieser Chronograph from the 3716 family, a 41 mm steel chronograph with a 30 minute counter at 12 o'clock, small seconds at 6, and no date window. Buyers should judge it on four things: case proportions, dial printing and subdial spacing, chronograph pusher feel, and the finish of the movement visible through the caseback.

What the IW371670 reference actually is

The 3716 family replaced the long running 3714 Portugieser Chronograph and moved the model to an in-house movement. The details that define the reference are consistent across the line, which is why a copy can be checked point by point.

• Case: 41 mm stainless steel, roughly 13 mm thick, with a narrow polished bezel and straight lugs.
• Dial: two subdials, applied Arabic numerals or batons depending on the variant, leaf shaped hands, and a fine railway track around the edge.
• Movement: IWC calibre 69355, a column wheel chronograph with a 46 hour power reserve and Pellaton style winding.
• Water resistance: rated to 3 bar, so it is a desk watch rather than a dive watch.
• No date: there is no date aperture at 3 o'clock on this reference.

The four checks that matter most on a replica IW371670

1. Case profile and thickness

A correct copy keeps the slim bezel and the flat caseband, and the lugs curve down toward the wrist instead of sticking out straight. Thickness is the usual giveaway. If the case sits noticeably taller than 13 mm, the movement inside is probably a thick chronograph module that was never designed for this case.

2. Dial printing and subdial position

Look at the railway track, the brand text, and the spacing between the two subdials. On a good replica the printing is crisp under a loupe, the numerals sit level, and the subdials are centred on the vertical axis. On a weak one the print looks soft, the minute track drifts, and the hands are flat rather than slightly domed.

3. What the subdials do

This is the most common failure point. The subdial at 12 must be the chronograph minute counter and the subdial at 6 must be the running seconds. Plenty of cheap copies flip that logic or fit a 12 hour totaliser instead, which is wrong for this reference. Start the chronograph and watch which hand moves.

4. Pusher feel and reset behaviour

Press the top pusher to start, the bottom one to stop, and the bottom one again to reset. The action should feel firm with a short travel, and the reset should snap both chronograph hands back to zero together. A mushy pusher or a lazy reset points to a low grade movement.

Movement options you will meet

Most replica IW371670 watches fall into two groups: Asian copies of the Valjoux 7750 architecture, often with modified subdial gearing, and clone column wheel movements built to imitate the layout of the 69355. The 7750 based versions are easier to service and cheaper to replace but usually add thickness. Column wheel clones are thinner and give a cleaner pusher feel, though spare parts are harder to find. Ask which base movement is used before you compare prices, because the name of a factory tells you less than the calibre inside.

Finishing details worth inspecting in person

• Caseback engraving: depth and sharpness of the lettering, and correct reference text.
• Hands: blued or rhodium finish, clean edges, no burrs under a loupe.
• Crystal: sapphire with a subtle anti reflective coating, not a domed mineral glass.
• Crown: signed, correct size, and smooth when winding.
• Strap: alligator grain leather with even stitching and a signed pin buckle or folding clasp.

How to wear and care for it

Keep the chronograph stopped most of the time, since running it constantly wears the movement faster. Avoid swimming regardless of what the listing claims, because the 3 bar rating on the original is not built for water. Wind or shake the watch gently to start it, set the time with the crown pulled out, and have the movement cleaned every few years if you wear it daily.

Quick answer for a first-time buyer

Pick a replica IW371670 by movement and measurements, not by marketing words. Confirm the 41 mm case, the 13 mm thickness, the 12 o'clock minute counter, the missing date, and the pusher action. If a seller cannot answer those four questions with specifics, the watch is a gamble.