Vintage Cloisonné Flower Brooch AB Rhinestone

This is such a light-weight, dainty piece. 8 petals on the bottom layer, 5 petals on the middle layer, 5 smaller petals surround a aurora borealis rhinestone. Golden enamel on the petals. It looks like gold tone on the top and a silver coating on the bottom. Not sure if it's silver-plated or some other type of plating. Estate jewelry. On the bottom the plating has chipped on one of the long petals. 1-1/2" in diameter