Short answer
A fake Aquatimer Automatic 44 is judged on four things: case dimensions, the internal bezel system at 2 o'clock, the movement beat rate, and dial printing under magnification. Get those four right and the watch passes at arm's length. Everything else, strap feel, caseback engraving, box and papers, is secondary. The genuine reference is an IWC Aquatimer Automatic 44, a 44mm steel dive watch rated to 300m with an inner rotating bezel driven by a second crown. Compare any replica against those hard numbers, not against photos.
Prerequisites
- Digital calipers that read to 0.1mm
- A 10x loupe or a phone macro lens
- The exact reference number you are comparing against, since dial colors and case finishes change per variant
- Bright directional light for checking anti-reflective coating and lume
Step-by-step inspection
- Measure the case diameter across the 9 to 3 line, excluding the crowns at 2 and 4 o'clock. The genuine case is 44mm. Anything reading 43.0mm or 45.0mm is a different case entirely, not a tolerance issue.
- Measure case thickness from the crystal top to the caseback. The genuine sits near 14.5mm. Thin replicas usually come in under 14mm because they use a slimmer movement and a flat caseback.
- Turn the crown at 2 o'clock and watch the inner bezel ring. It should move in smooth steps and stay where you leave it. A ring that creeps, or that only turns while you hold the crown, uses a friction system instead of the real ratchet.
- Check the crown at 4 o'clock for setting and winding. Threads should engage in the first half turn with no grinding and no wobble when unscrewed.
- Hold the crystal at an angle to a lamp. A proper anti-reflective coating kills most of the glare and leaves a faint blue or purple cast. A cheap replica either has no coating or one that turns the dial milky.
- Inspect dial text with the loupe. Look at stroke width, letter spacing and the alignment of the brand name against the 12 o'clock marker. Misaligned printing is the most common giveaway.
- Charge the lume with a flashlight for 20 seconds, then kill the room lights. Genuine grade lume glows bright and fades over hours. Weak lume fades in minutes.
- Check the date window. The aperture should be crisp with a beveled edge, and the date wheel font should match the dial printing in weight.
- Read the caseback engraving. Look for sharp letter edges and consistent depth. Laser-etched text on cheap replicas looks shallow and gray.
- Time the movement. Let it run for an hour, then count beats against a stopwatch. A 28,800 vph movement gives eight beats per second. A 21,600 vph movement gives six, and that is an instant tell for anyone who knows the reference.
- Ask for a water resistance test if you plan to swim. A dive style case that has never been pressure tested should be treated as splash resistant only.
Quality tiers you will see
- Entry tier: 21,600 vph movement, mineral glass, painted bezel ring, no anti-reflective coating.
- Mid tier: 28,800 vph movement, sapphire crystal, working inner bezel, correct 44mm case, lighter lume.
- Top tier: 28,800 vph movement with the correct jewel count and power reserve, double anti-reflective sapphire, correct case thickness, matched lume and printing.
Red flags
- Seller refuses to give caliper photos of the case
- Case diameter quoted as 42mm or 46mm for a 44mm reference
- Inner bezel that only turns clockwise while the crown is held
- Caseback photo that hides the serial area in shadow
- Movement described only as "automatic" with no beat rate given
Work through the list in order. Dimensions first, bezel second, movement third, cosmetics last. That sequence filters out most bad examples before you spend time on details that do not affect how the watch wears.