This Matilde Poulat  style "crown" brooch has been repurposed into  a pendant with an amethyst necklace.
The brooch appears to be a  Matl/Salas, with 6 amethyst faceted teardrops and 3 amethyst pyramids. There are 22 turquoise cabs and 4 coral cabs to complete the piece. In person, the piece is mesmerizing...I can't stop looking at it! All stones present and it's in excellent condition. The photo of the back shows the hallmarks, but they are impossible to decipher. 
The amethyst necklace features 6mm x 8mm smooth amethyst oval stones. There is 2" of sterling chain to make the necklace adjustable from 17.5" to 19.5". Both necklace lengths are shown in the photos provided. All findings are sterling.