Krupp Diamond: The Krupp Diamond originally came from the collection of Vera Krupp whose family supplied munitions to the Germany Army in World War II. Harry Winston purchased the diamond and the sold it to Richard Burton as a gift for Elizabeth Taylor for $305,000 in 1968. The diamond is one of her most prized possessions and she's worn it in every film she's made since it was given to her.
Ring Gun: This 19th century French ring concealed a tiny gun capable of firing six 5mm bullets. Its name, quite appropriately, was "Le Petite Protector." For this trigger finger to work, though, you'd have to be the sort of person who could discreetly pull off a good-sized ring.