Piece of Jewelry: Earrings
These were her favorite pair, and they were a gift from her grandfather-in-law, Louis XVI. They were taken from her when she and her family tried to flee France, and ended up in the hands of a Russian grand duchess sometime later. Cartier bought them in the 20th century, replaced the silver settings with platinum ones, added the triangle tops, a member of the Post family bought them, and they were finally donated to the Smithsonian in 1964. Supposedly the original silver settings were reinstated at that time.
2. Owner, Marie Louise of Austria, Napoleon I's second wife and double grandniece of Marie Antoinette.
Piece of Jewelry: Napoleon Diamond Necklace
Napoleon I commissioned the making of this necklace after Marie Louise gave birth to their son. She took it back to Austria with her after his regime collapsed, and it was passed down through the Habsburg family. It was sold to an industrialist and eventually resold to Harry Winston. The same member of the Post family bought it and donated it with Marie Antoinette's earrings to the Smithsonian.
Piece of Jewelry: her Tiara
Originally the tiara had emeralds instead of Persian turquoise. And yes, the Post woman bought it off of Van Cleef & Arpels.