Vintage 1930s locket with 3 rose cut garnets

This is an absolutely outstanding piece of antique jewelry - I would guess from the 30s or even older. I took it to our local gem shop to see if it could be gold; they said it is probably gold filled although it is not marked. They also said that the 3 red stones are rose cut garnets. It has room for 2 pictures or your could put in a lock of hair (there are already 2 pictures in it from that period). The locket measures about 1 inch long; it opens by pulling the 2 latches in the opposite directions. The chain is about 21 inches long and is marked gold filled. A must have for the collector of wonderful antique jewelry pieces.