The recent history of the "Regente" is somewhat mysterious: Bernard Morel states the diamond cap was made at a later date to mimic the original one (using old-mine diamonds).
He also uses the name Perle Napoléon, which is more correct that the name Régente, which was invented after 1887 to highlight the prestige of the provenance (thus associating the pearl with the Régent diamond).
One of the shoulder brooches was acquired by the Louvre recently:
Broche d’épaule de l’impératrice Eugénie, François Kramer, 1853, Perles, Diamants et Or. [Musée du Louvre-Société des Amis du Louvre]