I think Prince Lieven is mistaken.
The Tiffany was only discovered 7 years after Napoleon III's abdication and was sold directly to Tiffany's. There was never another owner.
It is similar in cut to the Regent diamond, however, which the Empress Eugenie did wear, but which was not sold by her and remains in the Louvre.
The Wittlesbach was never part of Louis XIV's collection.
Perhaps there is some confusion with the Hope, which was part of that king's treasury.