The principles are the same, you just need to find something that is silver so that you can sample the color to use. To get accurate colors for your artwork you should get real examples of items and take Pictures or find them on the internet and use Photoshop to sample the colors and save them as color swatches for later use. Remember that items do have reflections and shadows so try to get realistic samples and sample the different aspects of the colors of the items to make your artwork look more realistic.