Michelle Obama in the state dinner dress by designer Doo-Ri Chung. **See more detail in larger image, below** Her husband is wearing, well, a tux. We didn’t ask. (Alex Wong/Getty Images)

Chung did not know her gown was officially chosen until a call from the Washington Post confirmed her dream project Thursday night. “I wasn’t sure,” she said, reached on her way to a store opening in New York. The gown’s time in the spotlight was the culmination of weeks of work.

“We were contacted after our spring show,” Chung recalled. The first lady’s office told her that “they really loved the strapless purple gown.” But all parties both knew there were some modifications that needed to happen. “What we showed was a lot more risqué than what the First Lady could wear. Obviously a thigh-high slit would not work.” (**Updated, 11 p.m.: State dinner fashion; what the guests wore)

A more modest slit remained, leading up to a high-waisted belt. Chung noted that she accommodated a usual Michelle Obama accessory, while the First Lady respected the fabric choice that the designer favors. “Jersey, of course. Signature to the house!” she said with a laugh. “I appreciate the dress she asked for doesn’t veer off what I usually do.”

Why jersey? “I feel jersey is very comfortable.” Easier for dancing to Janelle Monáe? “Yes! I think so.”

The attached belt was made of crystals wrapped in chiffon and, of course, jersey, which played off the color that Chung said was a deep hue that changes in various light. “I wanted something with a little bit of an embellishment but it’s still very demure,” Chung explained. She did all the work without actually meeting the president’s wife, but worked carefully with her measurements. “We tried to keep it very close to the specs,” Chung said.

The First Lady has made a point of showcasing fashion upstarts and emperors alike, and Chung was enthused to be among them. “I love that she wears Isabel Toledo, Azzedine Alaia, Maria Cornejo,” she noted. “I love that she supports young designers.”

Five years ago, Chung won the Fashion Fund award for fresh talent, given by Council of Fashion Designers of America. In an earlier year, when she was finalist, her design process was captured by documentary cameras as she reverse-commuted from New York to her parents’ dry-cleaning facility in New Jersey. Their extra square-footage served as welcome studio space for a designer still building a following—and a revenue base.

Chung’s parents have been kept in the dark about the secret project for the First Lady. “I didn’t want to get their hopes up,” Chung confessed, though she knew they were keenly aware of the South Korean state visit. “They’re retired now. They come to all my shows.” But they would respect that their daughter had a few more stops in her busy day before she filled them in on her latest success.

“I will call them when I get home,” she said. Updated: Friday 12:30 p.m.

Read also:

South Korea state dinner: Who’s who on the guest list, and who got a seat at the head table, 8:58 p.m.

South Korea state dinner guest list, 6:29 p.m.

Michelle Obama’s South Korea state dinner dress, 7:32 p.m.

State dinner for Korea preview: Michelle Obama’s dresses; a history of state dinners, 1013/11

State dinner guest David Kim, and how he almost missed it, 10/12/11

White House state dinner for Korea: We try to guess the guests, 10/5/11

(Alex Wong/Getty Images)