Start With the Reference Number, Not the Photos

Top pick for vetting a listing labeled IW323764: a two-part check that first matches the watch against the manufacturer's own reference data, then confirms the movement and case finishing by hand. That pairing beats any single test, because counterfeiters copy what a photo shows, such as engraving, dial text and case shape, and rarely copy what a photo hides, such as movement decoration, clasp construction and service history.

The criteria below cover reference format, caseback engraving, dial and hands, movement, bracelet and clasp, and paperwork. Each section lists what supports authenticity, what raises doubt, and who should weight that check most.

What IW323764 tells you, and what it does not

IWC builds its catalog around structured reference numbers, and the brand publishes collection and technical data for its watches. A number printed in an online listing proves nothing by itself. Sellers apply plausible numbers to casebacks, warranty cards and ad copy, and a number that looks correct in a title can still sit on a watch assembled elsewhere. If a seller cannot say which collection the watch belongs to, or gives one number in the title and another in the description, treat the listing as unverified until you resolve the gap.

• Pros: the number matches across listing, caseback and card; the seller names the collection and caliber without hesitation; caseback photos are sharp enough to read the engraving.
• Cons: title and card disagree; no caseback photo at all; engraving in the wrong font or spacing; vague claims about a prototype or limited run with no documentation.

Best for: remote buyers who will never handle the watch before paying.

Criterion 1: Caseback Engraving and Case Finishing

Engraving is where most fakes give ground under magnification. Genuine engraving is crisp, cut to consistent depth, and uses letterforms that match the brand's own typography. Look at how the polished and brushed surfaces meet. A case that has been over-polished loses the sharp line where finishes change, and that is common on both worn originals and reworked fakes.

• Pros: consistent engraving depth, correct letterforms, signed crown, clean finish transitions at the lugs and bezel, correct caseback style for the stated model.
• Cons: soft or uneven engraving, misspelled words, rounded lug edges from heavy polishing, wrong caseback type, mismatched or stripped caseback screws.

Best for: buyers working from macro photos or a short in-person viewing.

Criterion 2: Dial, Hands and Crystal

Dial work separates a watch that was produced to a specification from one assembled from parts. Check index alignment against the printed track, the position of the date window, and the finish on the hands. Under a loupe or a phone macro lens, genuine printing has hard edges and no stray ink. Any fiber, dust or glue residue trapped under the crystal points to a case that has been opened outside a proper workshop.

• Pros: applied indices aligned with the dial print, centered date window, clean printing under magnification, correct hand finish, even anti-reflective coating.
• Cons: printed indices where applied ones belong, dust under the crystal, patchy lume, wrong date font, missing or shifted cyclops, chromatic haze from a single-sided coating.

Best for: anyone comparing seller photos against official brand photography side by side.

Criterion 3: Movement and Rotor Finish

The movement must match whatever caliber the manufacturer lists for that reference. Open the caseback or ask for movement photos with the rotor turned to show the bridges. Clones and generic ébauches are easy to spot once you know what decoration belongs on the caliber: anglage, striping, perlage and engraving all follow a house style, and unmodified blanks do not.

• Pros: correct caliber family for the reference, decorated bridges and rotor, engraved or stamped markings that match the case, serial present and legible, clean service marks.
• Cons: undecorated industrial movement, wrong jewel count or beat rate, mismatched rotor engraving, missing serial, adhesive residue or a parts sticker left on the rotor.

Best for: buyers paying a premium for a serviced example, or anyone with a watchmaker within driving distance.

Criterion 4: Bracelet, Clasp and End Links

Bracelets are expensive to make and expensive to fake well. Feel for play between links, check whether the bracelet uses screws or spring bars, and look at how the end links meet the case. On two-tone or gold-plated examples, wear patterns tell you whether the plating is thin.

• Pros: solid links, screws rather than friction pins, signed clasp with correct code, end links flush to the case, gradual taper that matches the reference.
• Cons: hollow stamped links, spring bars where screws belong, wrong clasp code, sharp unfinished edges, plating rubbed through at the clasp.

Best for: daily wearers who care about how the watch holds up after a year on the wrist.

Criterion 5: Box, Papers and Service History

Paperwork supports a watch, but it does not authenticate one on its own. Cards get reprinted and boxes get bought separately. What matters is a chain that holds together: matching numbers, a plausible sale date, a dealer or watchmaker who can be checked, and receipts that line up with the service stamps.

• Pros: card number matches the case, correct booklet and box for the era, service papers from an identifiable workshop, consistent ownership story.
• Cons: blank or reprinted card, mismatched serial, no box or papers on a watch priced far under market, pressure to pay outside a protected platform.

Best for: collectors and anyone who may resell later.

Where Replica Listings Usually Cut Corners

Listings that openly sell a replica IW323764 tend to be honest about the number being decorative and price the watch as a replica. The trouble starts when a replica is relisted as genuine. In that case the reference number is the marketing, and the tells show up in the movement, the clasp and the paperwork, in that order. If a seller refuses movement photos or a video call, the listed number is not worth debating.

Use-Case Recommendations

• Buying your first pre-owned IWC online: prioritize reference verification and documentation, and skip listings without caseback photos.
• Buying in person: prioritize the movement and the bracelet, since these are hardest to fake convincingly and easiest to inspect up close.
• Buying for resale value: originality and paperwork above all, because a mismatched card follows the watch forever.
• Deliberately shopping replica listings: expect the reference number to be cosmetic, pay replica money, and never pay genuine prices for a watch sold as a replica.

Bottom Line

A reference number is a claim, not a certificate. On a watch labeled IW323764, the deciding evidence sits in the movement, the engraving and the clasp, and those three checks answer more questions than any screenshot of a warranty card.