The top pick for a fake IW376063 is the high-tier build with a Swiss ETA 7750 base or a well-finished clone of it, a machined steel case, and reference-correct engraving on the back. Four criteria set that ranking: the chronograph has to start, stop and reset with the same pusher feel as the real watch; the case dimensions and crown geometry have to match the reference; the dial printing and applied markers have to survive a loupe; and the caseback has to carry the right reference number, serial and font. Below, the replica market splits into three tiers judged against those criteria, followed by the checks that expose everything that fails.

What the IW376063 actually is

IW376063 sits inside the IWC Aquatimer line: a steel dive chronograph with an internal rotating bezel and a screw-down crown under a sapphire crystal. Most Aquatimer chronographs of this generation run on an IWC-modified Valjoux 7750 base (caliber 79320 among others), and that base is what fixes the sub-dial layout and the pusher weight. Before you compare anything, pull the exact case size, caliber and reference spelling from IWC's own product page for the reference. Counterfeiters copy spec sheets that were already wrong, so a fake often disagrees with the catalog in the same places a bad listing does.

Tier 1: Swiss-movement build (top pick)

This is the only tier that behaves like a chronograph when you press the buttons. The movement is a genuine ETA 7750 or a close clone, the case is CNC-machined rather than cast, and the seller can tell you which factory produced it.

Pros

  • Correct sub-dial layout and a running seconds hand that sweeps instead of ticks
  • Pushers with defined travel and a crisp reset to zero
  • Case lines, lug bevels and crown threading that hold up in hand
  • Easier to service, because any watchmaker who knows a 7750 can open it

Cons

  • Highest cost of the three tiers
  • Water resistance is a claim, not a fact, until someone seals and pressure-tests it
  • Rotor engraving and finishing still differ from the original under magnification
  • Availability moves in batches, so sizes and dial variants come and go

Who it suits: buyers who wear the watch, use the chronograph, and care that a close look does not end the conversation.

Tier 2: Asian 7750 clone

The middle tier keeps the chronograph layout honest, which matters more than most buyers expect. The dial furniture is already right, so the remaining gaps sit in finishing and reliability.

Pros

  • Same sub-dial positions as the 7750-based original
  • Proper weight and pusher feel when the movement is a real chronograph and not a decorative module
  • Noticeably less money for a watch that still reads correctly on the wrist

Cons

  • Date changeover and chronograph reset can be sloppy
  • Rotor wobble and noisier winding
  • Shallower engraving on the caseback and a rotor finish that looks stamped
  • Many independent watchmakers decline to service it

Who it suits: buyers who want the correct dial and case proportions and accept that a service may cost more than the watch.

Tier 3: quartz and decorative chrono builds

These are costume pieces. Nothing about them is wrong if that is what you paid for, and everything about them is wrong if a seller calls it anything else.

Pros

  • Lowest cost by a wide margin
  • Keeps time without winding
  • Fine as a beater or a display piece

Cons

  • Ticking seconds hand, which is the fastest tell on a dive chronograph
  • Pushers that do nothing, or that only move a decorative hand
  • Light case and hollow-feeling bracelet or rubber
  • Printed sub-dials that never move

Who it suits: nobody shopping for a convincing IW376063. Skip this tier and save for Tier 1 or Tier 2.

The checks that end the conversation

  • Caseback engraving. Genuine engraving cuts deep with sharp shoulders and even stroke width. Fakes show shallow laser marks, soft edges, or one serial repeated across an entire production run.
  • Dial print and applied markers. Compare the letter spacing in the brand name, the thickness of the minute track, and the polish on the marker edges. Fakes get one of those three wrong almost every time.
  • Lume. Applied plots should sit flat inside their surrounds and glow evenly. Painted lume with visible brush edges belongs on a budget build.
  • Crystal and coating. IWC uses anti-reflective treatment on these crystals, so a flat, milky reflection with no tint is a warning sign.
  • Internal bezel action. The rotating ring should index in clean steps and stay aligned at the top marker. A bezel that drifts or wobbles after a turn was assembled without care.
  • Movement. Ask for a photo of the movement and the rotor, then compare the engraving and finish with reference photos. A closed caseback is not a reason to accept a mystery movement.
  • Weight and case finishing. Brushing should run one direction, lug bevels should catch light on a clean edge, and the watch should feel dense in the palm.
  • Water resistance. Treat every claim as unverified until a shop pressure-tests it. Fakes leak at the crown and caseback gasket first.

Box, papers and the price trap

A full set proves nothing on its own. Boxes, cards and manuals are easy to source, and a genuine set can be paired with a fake watch. Judge the watch first, the paperwork second. The other trap is price: secondary market values move, so no fixed number applies, but the rule holds. If a listing sits far under the going rate for the reference and the seller has a story about why, you are looking at a fake, whatever the listing says.

Bottom line

A fake IW376063 lives or dies on the movement and the caseback. Buy Tier 1 if you want pushers that work and a back that survives a loupe; buy Tier 2 if the dial layout matters more than the finish; ignore Tier 3. Then verify the reference against IWC's own specs before you spend anything.