Quick answer
A fake IW3716 exposes itself at the dial and the case back. Every genuine Portugieser Chronograph in the 3716 family has two subdials at 12 and 6, no date window, leaf shaped hands, and a 41 mm case. Behind the sapphire display back sits an in house calibre 69355 with a column wheel and a skeletonized rotor carrying the IWC medallion. Counterfeits built on an ETA 7750 or a Seagull ST19 show a date aperture, a thicker case, and a rotor with a printed logo or a shallow etch.
What you need before you start
- A digital caliper that reads to 0.1 mm.
- A 10x jeweler loupe or a macro lens for your phone.
- A bright, angled light source.
- Official reference photos of the exact 3716 variant you are inspecting.
- A scale that reads in grams.
- The seller, the box, and the paperwork in front of you.
Authentication steps
- Check the dial layout and confirm two subdials at 12 and 6 with no date window at 3.
- Measure the case with the caliper and confirm 41.0 mm across and roughly 13.1 mm thick.
- Weigh the watch head without the strap and compare it against published figures for the same reference.
- Study the subdial rings under the loupe and confirm the snailed texture is cut into metal rather than printed flat.
- Inspect the applied numerals and the leaf hands for a polished bevel on every edge.
- Read the dial text and confirm sharp edges and even spacing on IWC, SCHAFFHAUSEN, AUTOMATIC, and CHRONOGRAPH.
- Examine the crown and the two pushers and confirm a signed crown plus round pushers at 2 and 4 with short, firm travel.
- Run the chronograph and watch the central seconds hand start without a jump and reset to zero without hesitation.
- Check the case back engraving with the loupe and confirm the reference number, serial number, and Probus Scafusia mark are cut deep.
- Look through the sapphire case back and find the column wheel, blued screws, Geneva stripes, and the IWC medallion on the rotor.
- Compare that movement finish with reference photos of calibre 69355 to rule out a stock 7750 rotor.
- Inspect the strap and buckle and confirm Santoni alligator leather, dense stitching, and a signed pin buckle or deployant clasp.
- Match the reference number to the dial and case metal combination published by IWC for that number.
- Ask for the original invoice and warranty card, then verify the serial number with an IWC service center.
Why the movement settles the question
Dial work can be copied. Calibre 69355 cannot be copied at replica prices. The real movement runs at 28,800 vibrations per hour, holds a 46 hour power reserve, winds through a dual pawl system, and shows a column wheel under the bridge. A chronograph module stacked on a 7750 or an ST19 needs a date wheel somewhere in the train, which is why so many counterfeits grow a date window the genuine watch never had. If the seller will not let a watchmaker open the back, treat the watch as fake and walk.
Red flags that end the conversation
- A stainless steel 3716 offered well below used market value with no explanation.
- A seller who refuses clear photos of the movement and the case back.
- Box and papers reported lost on a watch only a few years old.
- Pushers that feel mushy, gritty, or loose in the case.
- Plating worn through on lug edges, crown guards, or the case flank.
- Serial number fonts that differ from the reference photos you brought.
When to bring in a professional
Book a service center inspection when the price sits in genuine territory, when the seller offers a short return window, or when the movement finish looks close but not exact. A watchmaker with the case back open can time the movement, confirm the column wheel, and read the serial in minutes. That fee is small next to the cost of a counterfeit sold at genuine money.