Saw a similar Barbie mod using the new Barbie Looks doll as a young Queen Charlotte from the Netflix series and had to have one for myself. If you haven't seen the series yet, it's wonderful.
This is the dress I started with, the Barbie French Court dress which I thought would look good even if it isn't the exact silhouette. (Stock photo from Mattel because I forgot to take a picture of the one I bought off ebay!)
Barbie French Court Dress by Kenai Queen, on Flickr
I tore it apart, put on lots of gold trim, shortened the sleeves and put a fall of lace on them, made the skirt a bit more poofy with some gathers and a tulle petticoat and then used some of my Barbie jewelry from my stash. I'm pretty happy with her.
QueenChar1 by Kenai Queen, on Flickr
QueenChar2 by Kenai Queen, on Flickr