I’ve included two detail pictures of Bilbo’s hands holding the shirt because the shirts are quite different. There was no opalescent or iridescent paint used in the silver area: just white, Payne’s grey, blue, green, crimson, and maybe some black as well? I think the gold part of the shirt in the second version did have a touch of actual shimmery gold paint. (It’s been a long time since I last looked at these scans.)
Acrylic paints on 25 x 20 cm watercolour paper.