So how does one go about painting a silver object? Mix black and white? Not exactly. Think of what colours you would start with to paint a mirror, because that's pretty much what you are doing. Someone commented on painting a mirror: "I once set up a full length mirror next to my easel to try that. I was beside myself."
The question might be better asked (and thus in the question is the answer), "How do I paint reflections?"
because that is what silver is. Whatever the surrounding environment is, there lies the clue to what will be observed in the object...really...that simple, and yet...that challenging. There is no magic answer in a particular mix of paints because it is always dependent on other elements. It's all about light and reflections. The answer is really to look closely, and paint the shapes and colours you see.
It's like a silver piece has its own moods and expressions, and how it behaves depends on what surrounds it. Interpreting these things is a delight for me, and is an excellent example of finding beauty in simple things!