the Talisman of Charlemagne. It's a pendant jewel which is also a reliquary. The two pieces of wood within the center are said to be fragments of the True Cross. It is said to have been found on his body when his burial was opened.
Charlemagne owned a sacred amulet in which a relic of the True Cross was placed between two sapphires. The amulet was buried with Charlemagne in 814, but it was exhumed about 200 years later by Otto III. Empress Josephine, wife of Napoleon, wore it at her coronation in 1804 and kept it with her the rest of her life. Later it passed to Napoleon III, and on his death, his widow gave it to the Archbishop of Rheims. I've left out a number of bits of it's history, because I could go on and on. But here is a link to a video produced through the Ecole de Van Cleef and Arpels about it's fascinating life story.
Have a great weekend!!!