Vintage circular mixed metal oversized statement necklace

This was my mom’s in the late 80s/early 90s (I think?) and I have loved wearing it as a statement piece over black dresses, turtlenecks, even under a plunging neckline. The mixed metals also make it perfect for pairing with black, brown, silver, gold, brass, etc. No jeweler’s marks, but based on the patina on the copper layer and the tarnish on the sterling silver layer I’d say those two are likely genuine metals. Top layer is something oxidized? Brass? Collar is made from multiple strands of a thin, black, leather type material which are sort of woven together with additional metal beads. Easy hook and loop closure.