How Do You Tell Sea Salvaged Gold From Not?

realeswatcher, that is a good question. In fact, I have never tried to pry
the accretions loose, so I really cannot tell you whether its 'into' the coin
or just marine debris accumulated on the surface. It does look like the latter, though, and easy to remove.
However, for me, a sea-salvage coin has to look like one, so I much prefer this condition, rather than a cleaned example from the Nuestra Señora de la Luz. It has a much more interesting story to tell, imo.
That was an incredible recovery by the way. I believe I still have the catalogue from that sale.

I would reason that a mint fresh 22ct or 90% gold coin would loose some of it's mint bloom if left in sea water for several decades.