The top pick for a replica IW323720 is a high-tier build with a machined (not cast) case and bracelet, a Miyota 9015 or a well-decorated clone automatic, sapphire with inner anti-reflective coating, and a date wheel printed in the correct font. Everything below comes back to six criteria: case and bracelet finishing, dial print and applied indices, movement choice, crystal and coating, caseback engraving, and how much QC evidence the seller will show before shipping.

One thing to settle first. IW3237 is the IWC Ingenieur Automatic reference family, and the trailing digits (the "20" in IW323720) are the variant code IWC uses to mark a specific case, dial and bracelet combination. Two sellers can list the same number and ship different dial colors. Confirm the variant in writing before you compare anything else.

Option 1: High-tier build (top pick)

This is the build that survives close inspection. Brushing and polishing should meet at a defined edge, the bracelet links should articulate without grit, and the crown should thread smoothly with a firm stop.

  • Pros: correct case proportions and lug geometry; sharp applied indices with clean lume fill; date font close to the original; sapphire that reads dark at an angle instead of washing out.
  • Cons: highest cost of the three tiers; batch quality drifts, so a good review from six months ago may not describe what ships today; water resistance still needs independent testing if you plan to swim.

Best for: daily wear, and buyers who will hold the watch next to reference photos and care about the bracelet feel.

Option 2: Mid-tier build

The mid tier usually shares a dial and case supplier with the high tier but cuts cost in the bracelet and the movement finishing.

  • Pros: noticeably cheaper; easier to find in stock; often the same dial print as the tier above.
  • Cons: bracelet edges can feel sharp on the inner links; end links may not sit flush against the case; the date wheel font is the most common tell; rotors can be noisy.

Best for: a first replica, occasional wear, or a buyer who intends to swap the bracelet for a strap anyway.

Option 3: Budget build

  • Pros: cheapest entry point; useful for testing whether the case shape suits your wrist before spending more.
  • Cons: stamped case with soft edges; hollow end links; printed rather than applied markers on some batches; mineral or uncoated crystal; poorly regulated movement that gains or loses time noticeably.

Best for: a beater or a gift, not for anyone who will compare it side by side with the real thing.

Criterion: movement

Two movements dominate this reference in replica form: the Miyota 9015 and decorated clones of Swiss automatics. The 9015 beats at 28,800 vibrations per hour with roughly 42 hours of power reserve, and spare parts are widely available. Clones can carry more decorative finishing, but a watchmaker may refuse to service one.

  • Pros of the 9015 route: serviceable, consistent rate, easy to regulate, smooth sweep.
  • Cons of the 9015 route: rotor noise is audible on a quiet room; the decoration does not match a Swiss movement.

Best for: anyone who keeps a watch more than two years. Buy the serviceable movement, not the prettier one.

Criterion: caseback and magnetic protection

Engraving depth, the crispness of the reference text, and the finish of the caseback edge are expensive to fake well, so they expose the tier fast. Ask for a straight-on photo under raking light. The Ingenieur line is built around a soft-iron inner cage for magnetic resistance, and most replicas skip it entirely, so treat magnetic claims as unverified unless the seller shows the inner assembly.

Criterion: QC photos before shipping

  1. Dial straight-on, no glare, so you can read the print and check index alignment.
  2. Date set to a two-digit day to judge the font and window cut.
  3. Caseback and clasp close-ups for engraving depth.
  4. Timegrapher shot showing rate and amplitude if the seller owns one.
  5. Bracelet on a flat surface to check link alignment and end-link fit.

Red flags

  • Stock photos instead of photos of the actual unit.
  • No named movement, only "high grade automatic."
  • Claims of identical water resistance with no pressure-test evidence.
  • A price far below the tier it claims to be, which usually means a downgraded batch.

Which build to buy

Choose the high tier if the watch will be worn often and handled by people who know the reference. Choose the mid tier if you want the dial and case right but do not care about bracelet refinement. Choose the budget tier only as a trial run. Keep expectations honest: a replica has no resale value and no manufacturer warranty, and selling counterfeit branded goods is illegal in the US, so treat any purchase as a personal, final transaction.