Vintage black & white earrings from Mexico

Purchased 30 years ago, these earrings are from Mexico and say alpaca Mexico on the back. The silver color is made up of copper, nickel, and zinc. It’s considered more durable than sterling. The mother of pearl inlay sits on a black background. On drop wires, these black-and-white earrings provide drama. They can be polished. About a 2” drop.