Short answer
"Omega 3604" is not a current model name in Omega's own catalog. In listings the number usually shows up in one of two ways: as a vintage case reference stamped on older Omega cases, or as a calibre or lot number a seller attaches because it pulls search traffic. So "fake Omega 3604" almost always means one of two things. Either you are trying to spot a counterfeit being sold as the real thing, or you are shopping for a first copy and want to know which version of that reference is worth paying for. Both paths need the same information.
Why the number by itself tells you little
A reference number is a fingerprint. Case size, lug width, dial layout, movement, and bezel insert all hang off it. When a listing says "3604 style" and shows three soft photos, the number is decoration. Ask which dimensions the case was built from, then compare those against the genuine spec. A seller who cannot answer that question has already answered it.
What the tier labels actually mean
Terms like first copy, AAA, 1:1, and super clone are marketing, not grades. Nobody certifies them, and the same factory output gets relabeled by different sellers. What separates a watch that reads correctly on the wrist from one that looks wrong in the hand comes down to three things.
- Case geometry. Thickness, lug curve, crown guard shape, and how tightly the bezel seats against the mid-case.
- Dial work. Applied indices, printing weight, date font and alignment, and lume that matches the hands.
- Movement. What is inside sets the beat rate, the crown feel, and how long the thing runs before it needs a watchmaker.
Checks I would run before paying
- Ask for video, not photos. Winding, date flip, bracelet flex, and the second hand sweeping.
- Request a timegrapher reading: rate, amplitude, beat error.
- Get a macro shot of the dial and the caseback engraving. Fuzzy lettering and shallow stamping are the usual tells.
- Confirm the crown screws down and the threads are not gritty.
- Get the return window in writing, and pay through a method that gives you a dispute path.
What a replica will never do
It will not go to Omega for service. There are no factory parts, no warranty card that means anything, and no precious metal hallmarks that hold up. Anyone who opens a caseback will notice the escapement long before they notice the dial. Water resistance is the biggest myth in this market. A "300m" line on a replica page is copied from the real spec sheet, not measured on a test bench. Treat any first copy as splash resistant at most, no matter what the listing promises.
The legal side, briefly
Watches carrying Omega trademarks without authorization are illegal to import and sell in the United States, and customs does seize shipments. Buying one for yourself is a different question than reselling one, but the practical risk is identical: if it arrives broken, or does not arrive, you have very little recourse.
The honest bottom line
Use the reference number as a starting point, not a guarantee. Compare dimensions, demand real media, and judge the seller by how they answer hard questions. That process tells you more about a watch than any tier label ever will.