Wow, the effects are very pretty. I have no experience with GIMP whatsoever, so the only thing I would suggest (you don't have to do this) is using more colors to make it stand out. I know you wanted to have your main color be gold, but maybe you could do thin streaks of pink and/or silver to add more variety, without taking the focus away from the silver.
I rate 7-9/10. I can't decide, but somewhere in that area is where I would rate this.