The short answer to why the IW371620 draws so many replicas is that its dial is easy to print and its movement is hard to fake. Buy on movement and case dimensions first, dial detail second, and seller proof last. A convincing copy gets the 41 mm steel case, the roughly 13 mm thickness and the twin subdial layout at 12 and 6 right. A weak copy matches the dial in a photo and falls apart the moment you press the pushers, turn the watch over, or set it next to a ruler.
Why this reference is a target
The Portugieser Chronograph is a clean design. Thin bezel, leaf hands, applied Arabic numerals, a fine railway minute track and two recessed subdials. There is very little on the dial to hide behind, so a printer with decent equipment can get close on the front. The back is a different story. The reference family runs the in-house 69355 caliber, a column wheel chronograph with about 46 hours of reserve at 4 Hz, and the case is rated to 3 bar. Replica makers work from a Valjoux 7750 base or a decorated Asian clone, and that choice drives the subdial spacing, the pusher feel and the case height. That gap between an easy front and a difficult back is the whole reason the model keeps appearing in replica catalogs and the whole reason quality varies so much between sellers.
What to check before you commit
- Movement and beat rate. Ask for the base caliber by name, not a marketing label. A 28,800 vph chronograph with a running small seconds at 6 and a 30 minute counter at 12 is the minimum. Anything quartz or a 21,600 vph unit is a different product.
- Case thickness. This is the single most reliable tell. The genuine case sits close to 13 mm. A 7750 based copy often lands nearer 14 mm, and the extra height shows at the lugs and under a cuff.
- Subdial position and depth. The two registers should sit on the vertical centerline, evenly spaced, with a visible step down into each recess. Flat printed circles are a red flag.
- Dial print and applied parts. Look for crisp railway track ticks, numerals with even lume fill, and a logo that is applied rather than stamped flat.
- Crystal and coating. A domed sapphire with anti-reflective coating on both faces should almost vanish at an angle. Cloudy or heavily blue glass means a cheaper build.
- Strap and clasp. Stitching density, edge paint and the firm click of a deployant tell you more about the factory than the box does.
- Proof of the actual unit. Request dated photos and a short video with the chronograph running, the reset snapping back to zero, and the case back in focus.
Parameter bands worth memorizing
- Case diameter: about 40.9 to 41 mm, steel, polished and brushed mix
- Case thickness: about 13.0 to 13.3 mm on the genuine reference
- Lug width: 20 mm
- Water resistance: 3 bar, which means splash resistance and nothing more
- Movement: column wheel chronograph, 4 Hz, roughly 46 hours of reserve
- Layout: running small seconds at 6, 30 minute chronograph counter at 12
- Pushers: firm start, clean stop, crisp reset to zero
Common pitfalls
- Buying from stock photos of a genuine watch. Only images of the exact unit count.
- Accepting the phrase Swiss made on a movement that is assembled in Asia. Ask for the caliber name and a photo of the rotor engraving.
- Trusting water resistance claims. Have any replica pressure tested before it goes near water, and assume nothing until then.
- Ignoring the seller's return terms. Without a written return window you have no leverage after delivery.
- Forgetting that a replica has no service network. A chronograph that needs a repair can cost more than the watch did.
- Overlooking import rules. In the US, Customs can seize counterfeit goods, and the loss lands on the buyer. See the CBP guidance on counterfeit goods before you order.
FAQ
Why do people search for the fake IW371620 specifically?
Because the genuine watch is a well known design with a simple dial, and the replica market answers demand for recognizable pieces. Searchers are usually trying to work out whether a copy they have seen is any good, or whether a watch offered to them is genuine.
Can a replica be called 1:1?
No. The term is marketing. Case thickness, movement architecture and finishing all differ, and a jeweler or an authorized dealer will spot the difference under a loupe in seconds.
Is buying one legal?
Rules vary by country. In the US, selling counterfeit goods is trademark infringement and importing them is prohibited, so a shipment can be seized with no refund. Check your local rules before you spend anything.
Will a replica keep time?
A well built 7750 based copy can hold reasonable time when it arrives, but the chronograph function and the reset are the parts that fail first. Test both within any return window.
What matters most if I only check one thing?
Case thickness and the movement behind it. Those two answers predict the subdial spacing, the pusher feel and how the watch wears, and no amount of good dial printing covers a thick case.