did you find a copper colored dime button or is that one of the silver ones?
Try Testors metallizer. It's buffable. I haven't used it on this but I use it all the time and even the non-buffable metalizer is buffable. Really gives it depth and you can use an airbrush to lay it on really light to make it subtle. I painted a resin sterling and people swore they good see the depth of metal. I love this stuff!