A replica Omega 3604 is worth your money only when the case profile, the dial print, and the movement match the vintage reference they claim to copy. Three checks decide it: a case diameter within about 2 mm of the original, a dial with centered logo and even minute track spacing, and a movement that hacks and hand-winds without grinding. Everything past that is cosmetic.

Know What You Are Comparing Against

Omega stamped numeric case references inside the casebacks of its mid-century watches. Builds sold under a 3604 number copy that pattern: a round case in the 34 mm to 36 mm range, slim lugs with a short lug-to-lug span, a domed crystal, and a plain three-hand dial with thin baton or arrow hands. If a listing shows a 42 mm case with crown guards and a ceramic bezel, it is a modern watch wearing a vintage reference number. Decide which one you want before you pay.

How to Check a Replica Omega 3604 Before Buying

  1. Ask the seller for the case diameter, thickness, and lug-to-lug span in millimeters, then compare those numbers with the published dimensions of the original.
  2. Request photos of the caseback, outside and inside, and look for stamped reference numbers with sharp edges and a caseback that sits flush against the case.
  3. Study the dial at 3x to 5x magnification and confirm the logo is centered above the 12 o'clock marker and the minute track spacing is even.
  4. Compare the hands to the dial and make sure all three share the same finish, the same length, and the same color as the original.
  5. Check the crystal height in a side profile photo, because a domed crystal should rise from the bezel line without a step.
  6. Confirm the movement type, its beat rate, and whether it hacks and hand-winds, since a 21,600 vph or 28,800 vph unit changes how the seconds hand sweeps.
  7. Ask about water resistance in plain terms and treat any claim beyond splash resistance as marketing, not spec.
  8. Inspect the bracelet end links, which should sit flush against the lugs with no gap and no rattle when you shake the watch.
  9. Get the return window and warranty in writing before payment, because a seller who refuses returns on a defect is a seller to skip.

Movement Options

  • Japanese automatics such as the Miyota 8215 or 9015: reliable, easy to service, common in entry and mid-tier builds.
  • Chinese automatics such as the Seagull ST21 or a 2824-style clone: closer case thickness, wider quality spread.
  • Swiss ETA or Sellita movements: found in the top tier, smoother winding, higher price.

Expect entry builds in the low hundreds of dollars, mid-tier builds in the mid hundreds, and Swiss-powered builds above that. A seller who quotes a Swiss movement at an entry price is describing a decorated Chinese movement.

Practical Limits of Any Replica

  • Omega will not service or authenticate a replica, and many independent watchmakers will decline to open the case.
  • Resale value is low and unstable, so treat the purchase as money spent.
  • Legality varies by country. Selling a counterfeit is illegal in the United States, and imported counterfeits can be seized at the border.
  • Water resistance is not guaranteed beyond splashes regardless of what the listing says.

Bottom Line

Buy the build that matches the original proportions and carries a movement you can have serviced. Skip anything with soft caseback stamping, a flat crystal, or a seller who will not put the return terms in writing.