Spectacular! I have never seen this Vendome brooch before, and probably never will again. Silvertone multi-layer construction, hand-soldered, with rhinestone chain, silvertone wire, and large clear rhinestones in rounds and ovals. The large oval stones are unfoiled, and sparkly quite brightly. Three of these large ovals dangle from the main part of the brooch, affixed with rhinestone chain. Excellent condition, and signed "(c)Vendome" on applied plate on reverse. The pin may also be worn as a pendant - it has a bale on the reverse for hanging. This is a large, bold pin: it measures 3.5" long.
Vendome was a label of Coro (Cohn & Rosenberger), and was used from 1944 to 1970. The copyright symbol means that this piece likely dates from the mid-1950s or the 1960s. Stylistically, I'm inclined to place it in the early 1960s.