The fastest way to judge a watch sold as an IWC IW328070 is to look past the case for a moment and check the two things that are hardest to copy: the movement inside and the engraving on the caseback, matched against the reference number in IWC's own records. If either one is wrong, nothing else on the watch matters. The criteria used here are the six that decide the outcome in practice: movement, case and crown geometry, dial printing, lume and hands, caseback engraving and serial, and the paperwork plus the seller's story. Price is not on the list, because counterfeit sellers price to the story, not to the watch.

Confirm What the Reference Number Is Supposed to Be

IWC reference numbers follow an IW prefix plus six digits, and the leading digits group related models into families. Before you judge any single watch, confirm the exact reference on IWC's own reference lookup, and note the case size, case material, dial variant, and movement family it should have. A watch that carries a real reference number but the wrong case size for that number is already a problem.

• Strength: takes two minutes and costs nothing, and it eliminates most bad listings before you handle them.
• Limit: older references drop out of current catalogs, so an absent listing is not proof either way.

Ask the seller for a clear photo of the caseback and the reference engraving before anything else. Sellers who sell replicas tend to send dial shots and avoid the back.

The Movement Is the Decisive Test

Cases and dials can be copied close to the original. Movement architecture is where replicas fall apart, because building a movement with the correct finish, rotor engraving, jewel count, and rate is expensive. Open the caseback, or have a watchmaker do it, and compare what you see with the movement family the reference should use.

• What it catches: wrong calibre family, mismatched rotor text, poor finishing on bridges, incorrect jewel count, a plain undecorated base movement under a decorated rotor.
• Where it fails: a franken watch with a genuine movement in a copied case, and any watch you cannot open before buying.

If the seller refuses an inspection by a third party watchmaker, treat that as the answer and walk away.

Case, Crown, and Crystal

Check the proportions first: lug width, lug to lug distance, case thickness, and the shape of the lug curve. Copies often get the diameter right and the thickness or curvature wrong, which shows up on the wrist long before it shows up in photos. Then check the crown for correct engraving, correct thread feel, and smooth winding or setting. A crown that wobbles in the tube or grinds on the threads is a signal.

• What it catches: budget cases, soft lug edges, mismatched crown logos, crystal height sitting proud of the bezel.
• Where it fails: higher grade replicas that use machined cases close to spec.

Use calipers if you can. Guessing at 0.3 mm by eye is not a check.

Dial Printing, Lume, and Hands

Dial text is printed, not engraved, and the print on a good watch sits flat and sharp under magnification. Look for fuzzy edges on the logo, uneven spacing between letters, and dial text that does not match the reference variant. Lume is the second giveaway: genuine lume charges and fades with a consistent tone across the markers, while copies often show patchy glow, a green marker next to a blue one, or markers that glow through the print.

• What it catches: misaligned date wheels, wrong date font, sloppy indices, hands with the wrong length or the wrong tip shape.
• Where it fails: a genuine dial in a copy case, which only a movement and caseback check will settle.

Caseback Engraving and Serial Numbers

Engraving quality matters more than the number itself. Genuine engraving is cut or laser etched with even depth and clean edges. Copies often show shallow, rounded, or uneven lettering. Note the serial number and compare it with any documentation, then contact IWC service with the reference and serial to confirm the watch exists as described.

• What it catches: duplicate serials, wrong font, missing reference digits, engraved text that does not match the case material.
• Where it fails: nothing, if you actually call the brand. Verification by the manufacturer is the strongest single step available to a buyer.

Box, Papers, and the Seller Story

Paperwork is easy to fake and easy to buy separately, so treat it as supporting evidence and not as proof. Ask where the watch came from, who serviced it, and why it is being sold. Vague answers, a rushed sale, or a price far below the market for that reference are all part of the same pattern.

• Strength: cheap and fast, and it filters out most bad deals.
• Limit: a confident story proves nothing about the watch itself.

Which Check to Use in Which Situation

• Buying online with no inspection: lead with the caseback photo, the serial, and a manufacturer verification. Skip the watch if any of the three is unavailable.
• Buying in person: bring calipers and a loupe, then insist on opening the caseback with the seller present.
• Inherited or already owned watch: go straight to a watchmaker for a movement inspection, then verify the reference and serial with the brand.
• Comparing two listings at similar prices: choose the one that allows inspection and offers a documented service history.

No single photo settles the question of whether an IW328070 style watch is real. A movement inspection plus manufacturer verification does, and everything else is supporting detail.