Her predecessor, Michelle Obama, often had dresses altered to her specifications — and wore an Atelier Versace chain mail couture gown to her final state dinner with then-Italian Prime Minister Matteo Renzi — but couture is a sector unto itself, rooted in French history, unabashedly elite, and symbolic of what is known with pride as “savoir-faire,” or know how.

It is also handmade to order, exists only as one-offs, and comes complete with prices that can run into the six digits. Mrs. Trump, for example, seems to have taken what was originally a jumpsuit from the Chanel spring 2018 couture collection and had it remade as a dress.

But in a world of Trumpian excess, where the first lady once wore a coat that cost $51,500, maybe such a willingness to spend should have been expected (besides, the dress can be donated to the national archive by the designer, which defrays the cost). Mrs. Trump has always been unapologetic about the price of her clothes, and this gown had a dual purpose.

As Louise Linton, wife of the Treasury secretary, Steven Mnuchin, said when she and her husband made their entrance, she was excited for “everything French!”

[Read more about President Trump’s first state dinner.]

There was something ironic about the fact she said that while wearing a silver beaded gown from Roberto Cavalli, an Italian brand designed by an Englishman, but it may not have occurred to her.