Vintage 1980s Ben Amun Brooch Japonaiserie Stone Form Plastic Resin

This is an unusual but beautiful brooch made by Ben-Amun. The Ben-Amun brand was established by Isaac Manevitz during the early 1980s. The brand has been embraced by many celebrities over the years including Jackie Onassis and many actresses and singers. I believe that this is an older piece as I cant find a similar example anywhere on-line. It is made in a stone form, although the stone appears to be made of some sort of thermoplastic or other synthetic resin made to resemble a stone with deposits in it - you can see a drilled hole in the side of the piece that I assume was used in conjunction with a mold. It has a floral form copper metal piece applied to the front. The brooch measures 2 1/2 by 1 5/8 with a depth of about 3/4 - it weighs 41 grams (1.5 oz). The back is signed Ben-Amun.
Nice piece of high-end costume jewelry - wonderful addition to a collection!