Quick answer
The Omega 3520 is not a watch. It is a movement, a chronometer-rated automatic from the 1990s and 2000s, and it sits inside genuine Constellation, De Ville and some Seamaster references. So a listing that says "replica Omega 3520" is describing a fake of one of those watches, not a copy of the caliber itself. Nobody out there is cloning the 3520 as a movement.
What the real 3520 is
Omega built the 3520 on the ETA 2892-A2 platform and sent it to COSC for chronometer certification. That is the whole point of the number: the 1120 is the standard version, the 3520 is the certified one. Specs people usually ask about:
- 21 jewels, 28,800 vibrations per hour
- Roughly 44 hours of power reserve
- Quick-set date
- Rhodium-plated finish with an engraved rotor
It is a thin movement, which is why the watches around it wear flat on the wrist. If you have handled a genuine 1999 De Ville or a Constellation of the same era, you have handled this caliber.
Why the number shows up in replica listings
Sellers borrow movement names because buyers search for them. A replica listing saying "3520" is telling you which genuine watch the case and dial are imitating. It is not telling you what is inside the case.
What is actually inside is usually a generic automatic from a third-party factory, sometimes a decorated clone with an engraved rotor meant to look the part. COSC certification is a paid, per-movement process. No replica workshop sends its output in for that, and no replica caliber carries a valid chronometer certificate.
Where replica 3520 listings get hazy
Case diameter, dial printing, the placement of the date window, the wording at six o'clock, the finish on the hands. Photos are often of a sample, not the piece you receive. I look for listings that show the same watch from a dozen angles under natural light, because that tells you the seller has the actual item in hand.
Legal and practical reality in the US
Counterfeit trademarked goods are illegal to sell and to import, and CBP seizes shipments when it finds them. Buying carries its own risk: no manufacturer warranty, no service parts, and water resistance claims that were never tested. A replica rated to 100 meters on a page may not survive a sink.
How to confirm a genuine 3520
- Rotor engraving is crisp, not stamped and shallow
- "Chronometer" and COSC references match the reference number
- Movement finish is consistent under a loupe
- Serial and caseback numbers line up with the dial configuration
- A watchmaker can confirm the base plate in minutes
The takeaway
Treat "3520" in a replica listing as a description of the original, not a promise about the mechanics. If the movement matters to you, that is the one part of the watch a replica cannot deliver, and it is the reason to look at a genuine example instead.