Washing metals sewn on fabric
I am currently in the process of creating a Fem!Russia from Hetalia: Beautiful World. The fabric I am using is a blizzard fleece, both in a pink and a white with a better quality costume satin from Casa Collection as a liner. All the fabrics are washable, which makes me happy seeing it's gonna be pink and white. My concern is over the cross accents on the coat and collar. I have bought eight 'gold' crosses that were used for jewelry making and I am going to sew it to the coat. I don't know if I should 'treat' the crosses before I sew it onto the coat because I am concerned that when I do wash the coat with the crosses on it, something bad will happen. Something like rust, transition of other metallic materials that could stain the fabric.