In this final episode, Ellie Harrison and Dallas Campbell reveal the greatest treasures we've ever created. Dallas braves vicious currents to dive on a shipwreck where gold, silver and 5,000 emeralds have been found. Ellie tells the tale of intrigue and obsession surrounding a jewelled room in Russia decorated with millions of pounds worth of amber; and she enters the secretive world of the diamond cutters - each lives with the knowledge that a slip of the hand could cost them millions of pounds.