Thanks all for your welcoming!
Caitlin, I wore it daily for 20 years, but I'm in the countryside since 2002, so... not convenient since ;-)
Tucs and CathyKeshi thank you, I can say it is end of 19th century from the original mount. It probably was born as a hat pin, there was at the time wonderful made from "soufflures de perles" adorned with rosecut diamonds!
I'm an antique jewellery collector since my 18 and am now 57.
I'm French, and bought it in 1992 in an antique mail in Paris. Seller thought it was too big to be true and sold it for the mount price! As it was Xmas time, I even got a bottle of Champagne with it :-D
BWeaves, thank you, she has a name! I call her Mazda (French brand of light bulbs) ;-)