I think oil-rubbed bronze switch plates would work if they look with the stone in the backsplash.

Can you post a picture of the backsplash stone please?

If you haven't already put the backsplash up, I recommend redoing the drywall behind it and rewiring the outlets so that they're up in a strip under the cabinets. my sister had this done and it looks so much better to not have a bunch of holes cut through beautiful stone.

[https://www.houzz.com/photos/undercabinet-electrical-plugs-phbr0lbl-bl~l_43508[(https://www.houzz.com/photos/undercabinet-electrical-plugs-phbr0lbl-bl~l_43508)

The only place you want to have outlets on the wall (or up from the base cabinet) is for those appliances that you keep on the counter all the time. For other outlets that are rarely if ever used, I like the look of hiding them.

oops. Just read the OP fully and realized you said switch plates. I was thinking all electrical. Sorry! okay to disregard my comment.