Answer first
Hippocampus is the collector name for the seahorse emblem Omega strikes on Seamaster casebacks. It is not a model name. No Omega line is called Hippocampus. On watches sold in 2013 the emblem sits on the solid caseback of the Seamaster Professional 300M. Aqua Terra and Planet Ocean models of the same year use a sapphire display back, so the emblem is not on the outside at all. A replica hippocampus fails on three points: relief depth, seahorse anatomy, and the lettering that runs around it.
Where the emblem sits on a 2013 watch
- Seamaster Professional 300M, caliber 2500: solid steel caseback, hippocampus in relief in the center, brand text and model text around it, reference number and serial number below.
- Aqua Terra, caliber 8500: sapphire display back. The rotor and bridges are visible. Check the caliber number before you expect an emblem on the outside.
- Planet Ocean, caliber 8500: sapphire display back on most references from that year.
If your watch has a display back and no outer emblem, that is normal for those references. A solid caseback on an Aqua Terra from 2013 is a mismatch and worth a second look.
What a real 2013 hippocampus looks like
- Relief. The seahorse is raised. The field around it is flat and level.
- Edges. Struck metal has clean edges and a shadow line under the body.
- Anatomy. A defined snout, one eye, a ridge along the back, and a tail that curls into a visible spiral.
- Text ring. The wordmark and the model text sit on a circle with even gaps between letters.
- Numbers. The reference number and the serial number are cut into the same caseback. The cut matches the text in depth and finish.
Replica tells
- Shallow relief. The seahorse reads as flat art, not struck metal.
- Soft edges. Fins blend into the body. The tail spiral closes up.
- Wrong scale. The emblem is small, or it crowds the text ring.
- Wrong font. The model script has thin strokes or a changed tail on the first letter.
- Mixed engraving. The serial number looks deeper or sharper than the reference number beside it.
- Fresh caseback on an old case. Thread pitch, brushing direction, and wear do not match the rest of the watch.
How to check a 2013 watch
- Read the reference number off the caseback.
- Find photos of that exact reference from the same production run.
- Compare the emblem at 10x magnification. Do not judge from a phone screen.
- Check the caliber number against the reference. A 300M from 2013 runs a different movement than an Aqua Terra.
- Compare the crown, the caseback threads, and the bracelet end links for wear that matches the case.
What is not known
Omega has not published an archive of the hippocampus dies or the emblem variants. Two 2013 Seamasters from different batches can show small differences in strike depth. One photo is weak evidence. Use the reference number, the caliber, and the caseback as a set.