NEWBURYPORT — Petit Bijou owner Richard Coco celebrated the one-month birthday of his store in a big way Monday when Kelly Clarkson went on a shopping spree.

"She gave me her credit card and license, and I said you must get teased a lot because you look like Kelly Clarkson," Coco said. "She said, well I am Kelly Clarkson."

Clarkson, her mother, sister and a small child were visiting for the day while staying with friends in Portsmouth when they stopped in the 10 State St. store.

"I didn't know what to think," Coco said. "My wife is a big 'American Idol' fan, and she was always our favorite."

As the American Idol winner browsed the store, Clarkson's mother pointed out two vivid paintings hung on the store walls.

One titled "Blue Rose," and the other, "Cello," both by Lawrence painter Javier Osorio, originally of South America, immediately captured Clarkson's attention.

"She loved them," Coco said. "I always said it would take a certain someone to buy these paintings, and it's nice it was a local artist."

When Clarkson told Coco she would take both, he, then unaware of her day job, made sure she knew the price tag of the art work.

"I said, you do know one is $1,400 and the other is $1,600?" Coco said. "She said she would take them both and asked if I would mail them to her."

Clarkson had the paintings shipped to her home state of Texas and also bought a headband, pendant necklace and bangle bracelets. Though Coco is tight-lipped about how much the singer spent, he did say the bill was in the thousands.

"I only had two sales yesterday," Coco said. "She was my second, and it was a big sale."

Clarkson spent a half-hour in the store trying on the various jewelry, hair pieces and handbags the new store sells before moving on to other downtown businesses.

"I said it was nice to meet you and I hope you come back to Newburyport soon," Coco said. "Then she left her gold card, so I had to run down the street and chase her to give it back."

Chamber of Commerce President Ann Ormond says Clarkson's visit is a testament to the city's downtown tourism.

"You never know who is going to pop up downtown," Ormond said. "She flew under the radar, and we heard about it the next day. That's the thing about Newburyport; you can get so lost in the beauty and magic of it that you're not looking for celebrities like you would be in Boston."

Coco said he immediately called his wife, Brigitte, with whom he co-owns the store. The store name is a tribute to his wife's French roots, and her mother Lucienne Rey, also an American Idol fan, works in the store.

"Brigitte is at a trade show in New York and was freaking out and screaming," Coco said. "We hope she comes back and visits soon."