This pendant has an open area in between two antique watch movement plates. The circle is made using an antique watch spring and then attached on the side with a silver plated bail on the back. There is a plate on the bottom from the Atlas Watch company, that only made watches until 1898, so that bottom piece is more than 100 years old. The top piece is from a Plan Watch Company piece and is from the 1800’s as well. There is a large Peridot, in the center of that piece. This hangs with a silver plated chain.
It can be purchased here:
https://squareup.com/store/antiquarian-couture/item/atlas-watch-pendant-with-large-peridot