Quick answer
A replica Portofino small seconds 39 is a copy of the IWC Portofino Automatic with the seconds subdial at 6 o'clock, sized around 39 mm. Most reps in that listing bracket sell for $280 to $600 depending on the movement, and the one detail that separates a good one from a bad one is the small seconds itself. If the subdial hand stutters, sits off center, or sweeps in a strange way, the watch fails visually no matter how nice the case looks. Case polish and dial print are easy for a factory to get right. A small seconds module that was never built properly is not.
What the "39" actually means
IWC has moved the Portofino case size around across generations, with small seconds models offered at 34 mm, 37 mm, and larger at different points. A listing that says 39 does not always map to one clean reference number. Before you compare anything, ask the seller for the case diameter measured with calipers, or a photo of the watch next to a ruler. Ask for lug to lug too, because that number drives how it wears. A 39 mm Portofino with 20 mm lugs usually lands near 45 mm lug to lug, which sits well on wrists from about 6.3 to 7.5 inches.
The movement, and why the subdial is the tell
Genuine Portofino small seconds watches use an IWC caliber built on a Sellita base with a small seconds train. Most replicas start with a Miyota 9015 or a Chinese automatic and bolt on a module to relocate the seconds hand to 6 o'clock. That module is where the shortcuts live.
- Subdial behavior: one full revolution per minute, a smooth sweep, no stutter and no lag.
- Height: modules add thickness. Ask for a caliper photo. Anything over roughly 12 mm on a dress watch this size reads wrong on the wrist.
- Setting: pull the crown to the first position and check the date flips cleanly, then the second position to confirm hacking.
- Date window: the aperture at 3 should be crisp and centered, with a white disc and clean black print.
Dial, case, and other tells I check
Leaf shaped hands are hard to fake at this price. Look for an even finish along the hand, no tool marks, and no wobble against the dial. Applied markers should sit flat, and print should stay sharp under a loupe, especially the IWC and Schaffhausen line and the spacing between Portofino and Automatic. Case finishing on this model is mostly polished, so any brushed patches on the bezel or lug tops stand out. The caseback on genuine pieces is solid with engraving that has real depth. Shallow laser etching shows up often on cheaper reps. The crystal should be sapphire with anti reflective coating, which you can spot by the faint tint at an angle.
Water resistance and daily wear
Treat any claimed rating as marketing copy. A rep with a press fit caseback and generic gaskets is splash resistant at best. I would not swim in one and would not take it into a shower. If you want to wear it near water, have a watchmaker pressure test it first, and understand the seals are still the weak point. Servicing is the other problem. Most watchmakers will not touch a counterfeit, so a failed movement often means replacing the whole watch rather than repairing it.
What it costs and what you give up
Expect $280 to $600 for a mid to upper tier rep, and more for one advertised with a Swiss or Sellita movement, though the word Swiss gets used loosely in this market. A genuine steel Portofino small seconds on leather runs roughly $5,500 to $6,500 at retail. The gap is real, and so are the tradeoffs: no warranty, no service network, no resale value, and legal exposure. Buying or selling counterfeit goods can carry civil and criminal penalties in the US. If you want a watch to pass down or trade later, this is not it. If you want the look on your wrist for a fraction of the price, a rep gets you close, and the subdial is the part you will notice every time you check the time.