Lol I was wondering when I got downvoted like crazy when I was posting this quote!
For naysayers, the reason the original quote source is not easy to find is because most quotes in that era were only recorded in books and newspapers, then printed and reprinted, and they aren't archived and searchable like media today (some are, most not). There can be discrepancies in the wording (I've seen this one with magical, dazzling, historical, and one-of-a-kind) because it's like the telephone game and newspapers took some liberties.
I don't have time to do as much of a deep dive on this as I'd like, but the book Marilyn in Fashion contains the quote about wanting a "historical" dress from Jean Louis. It was published in 2012, four years before Ripley's acquired the dress. I'm 100% positive that author found the quote in another source.