was is some tourist thing? you pick your own pearl...?
if so may be a fake... the chances of just picking up a shell and there being a pearl inside is slim ... you'd have to prise open the shell and remove the animal and look inside...
A real pearl will feel rough if you run it across your teeth. Fake are smooth. It is more than likely cultured pearl, (they insert a grain of sand into it, to irritate and cause it to produce nacre).
Cultured are the ones they pop in tanks at holiday places and cruise ships. You then "fish" for your own pearl.
It was at tenerife pearl...its real....and they had a collection of the shells and i picked one...apparently there were different coloured ones had different meanings....cant even remember how much it was lol..x