Here is the full list of all 12 Captain Sabertooth and the Magic Diamond achievements.
Travelled to Invisible Isle for the first time.
All islands have been visited.
Found all pirate hat collectibles.
Found all model ship collectibles.
Found all turtle statue collecibles.
Found all monkey statue collectibles.
All Souvenirs have been found.
All of Sabertooth’s rings have been found.
Completed all Captain’s Challenge rooms.
All dig spots have been dug.
All chests in the game have been found.
All Sabertooth flags have been found on, that appear on 2nd playthrough.