Short answer
"Fake hippocampus 2013" is a search phrase, not a model name. Hippocampus is the Chinese nickname for the Omega Seamaster (海马, literally seahorse), and 2013 is the year buyers pin to one of the first big waves of high-grade Seamaster replicas. So the phrase almost always points to a counterfeit Seamaster sold as a 2013 reference, usually an Aqua Terra 150M, a Planet Ocean 600M, or a Diver 300M.
Why the name travels
Chinese collectors and sellers call the Seamaster "Hippocampus," which is just the Latin word for seahorse. Listings on Chinese marketplaces get machine-translated into English, so the nickname leaks into Western search results alongside the year the seller bought or copied the watch. If you see "hippocampus" in a listing title, you are looking at a translated Asian-market ad, not an official Omega name.
What 2013 covers on those listings
The year is loose. Sellers use it for a handful of references that were current around then:
- Aqua Terra 150M with the calibre 8500, sapphire display back, teak-pattern dial.
- Planet Ocean 600M with the 8500 and a ceramic bezel insert with Liquidmetal numerals.
- Aqua Terra >15,000 gauss, the first Master Co-Axial, launched in 2013.
- Seamaster Diver 300M with the calibre 2500D and the wave dial.
The tells that survive a photo check
Movement and caseback
A real 8500 is an in-house co-axial with a free-sprung balance and a silicon Si14 hairspring. Most fakes run an ETA 2824 or Sellita SW200 clone, sometimes with a printed plate or an over-decorated rotor. On an Aqua Terra the back is sapphire, so open the photos and compare the bridge shape and jewel layout to a real 8500. When a listing only shows a solid caseback on a watch that should have a display back, that is your answer.
Bezel and dial
The 2013 Planet Ocean uses a ceramic insert with Liquidmetal numerals, flush and smooth, no raised paint. Fakes use painted or stick-on inserts. Ask for a video of the bezel turning: the genuine article has 120 clean clicks with no back play. Check the date window bevel and font too, since that is where cheap dial printing shows first.
Case hardware
The Diver 300M has a functional helium escape valve at 10 o'clock. On fakes it is often decorative, the wrong diameter, or stuck. Crown guard shape and the crown's signed logo are worth a zoom. Lug width matters: a 42mm Planet Ocean takes a 20mm strap, and a bracelet that rattles or leaves a gap at the end links is a bad sign.
Weight and finish
A steel 42mm Planet Ocean on a bracelet lands near 200 grams. Replicas run light because the case metal is thinner and the bracelet is hollow. Run your thumb along the case flank, where brushing should be even and the polished chamfer should be crisp.
Buying checklist
- Ask for the full reference number and look up the real specs for that reference.
- Request movement photos, either through a display back or with the caseback off.
- Ask for a video: seconds hand sweep, date change, bezel clicks.
- Compare dial text, date font, and logo spacing to a verified photo.
- Check that the serial on the lug and the card match, and that the card dates make sense.
- Price it. A used 2013 Aqua Terra sits around $2,800 to $4,500 and a Planet Ocean around $3,000 to $4,000. Anything at a few hundred dollars is a replica, no forensics needed.
What a replica cannot copy
The antimagnetic rating is the cleanest tell. A 2013 Master Co-Axial Aqua Terra is rated past 15,000 gauss, and a fake with a plain steel movement cannot come close. You will not test that at a meetup, but the dial text and caseback engraving should match the rating. The co-axial escapement itself is the other one. Replica makers clone the look of the rotor and plates, not the mechanism, and that shows up in service records and in how the watch holds rate over months.
If the seller leans hard on the word "hippocampus" and never gives a reference number, treat the listing as a replica and move on.