Michelle Obama, who ditched the boxy jackets and dowdy style of so many first ladies before her, addressed the Democratic National Convention in a flouncy, bright blue dress by designer Christian Siriano.
Never predictable or boring when it comes to clothes, her choice was in line with the modern and cool approach she has taken for the last eight years.
"Stuffy is not her signature, and in that sense her fashion choices reflect that sensibility and the mood of the times," said Avril Graham, executive fashion and beauty editor for Harper's Bazaar magazine.
Mrs. Obama wore her hair loose, parted to one side, with the cap-sleeve dress. Her jewelry was minimal, large silver earrings a prominent touch.
Fashionistas will miss this first lady, Graham said.
"I think it's fair to say Michelle Obama has been the darling of the fashion set. She has championed young design talent and highlighted existing designer names with a very confident approach to her wardrobe choices," she said.
The 30-year-old Siriano, who won the fourth season of "Project Runway" in 2008, has been growing his New York-based brand ever since. His convention creation included high-belt detailing, a tight bodice and a flared, pleated hem that lent the first lady movement.
Siriano dressed Mrs. Obama for the first time for a much sadder occasion: a black dress for the memorial service for five police officers killed by a sniper in Dallas earlier this month.
Mrs. Obama wears color and prints with confidence and mixes up the clothing shapes, or silhouettes, she chooses. She has worn an eclectic roster of designers, from the Europeans to the home-grown. Among her favorites: Jason Wu, Michael Kors, Narciso Rodriguez, Thakoon, Azzedine Alaia, Sophie Theallet, Naeem Khan and Junya Watanabe.
"Right from her early days as first lady she made the fashion elite take note," Graham said.
But she's no label snob, donning mom cardigans and other pieces from J. Crew and Gap. And she's been clever in her attitude to beauty, Graham said, experimenting with different hair and makeup styles that are of the moment.