The fabric is generally called cloth of gold. If it's silk and gold, it's samite. I wouldn't call that a dress, by the way. I don't know what the word for it is, but to use the Persian word in italics would probably be a good way to go.
It really depends how it was made and out of what kind of material. This could perhaps be described as gold and silk brocade, where the silk fabric was interwoven with threads of gold into intricate patterns in a raised design.