This monster of a necklace was, of course, reproduced after sketches of the original diamond necklace for which the real diamond necklace affair happened. The prop appears in the Norma Shearer version of Marie Antoinette from 1938 and then makes another appearance in A Philidelphia Story.
Though certainly not the same necklace, the design was reproduced for the 2001 The Affair of the Necklace, starring Hillary Swank.
If you have not read about the true story of the diamond necklace affair, I would highly suggest Antonia Fraser's magnificent biography on Marie Antoinette, entitled The Journey. The book gives great insight into the event, and is well worth the read.
A reproduction of the "Collier de la Reine" (at left) can be seen at the Château de Breteuil, France.