Antique Gold-Tone 3D Carved Pendant Necklace Intricate Floral Relief

Intricate 3D design on this antique/vintage pendant necklace. Appears to be bronze plated or brass, but I’m not sure. The pendant was made by casting, engraving and polishing. Has markings that are really hard to make out - either D & D or D & R? Maybe? See last 2 pics and see if you can make the stamp out. Very old and very hard to make out. Most likely depression era.