Credit: farfetch.com
Amal's floral jumpsuit is vintage Versace. I spent ages looking for the make of the jumpsuit and found nothing until I saw these pictures of a very similar vintage Gianni Versace dress at farfetch.com. Amal has been photographed wearing this jumpsuit before so it's clearly among her favorites and rare too.
Nice to she that she appreciates vintage classic pieces. Click here for the page at farfetch