Joss Stone’s image, from vocal cords on down

It doesn’t take long for a meeting with Joss Stone to descend into the surreal.

There she is, on a sofa in a Midtown recording studio lounge, watching music videos, chatting about her unlikely career as a soul singer, when her attention gets distracted ... by her own voice.

“Look, look, look,” she says. “Oh, my God!”

From a large-screen TV, Stone’s Gap commercial is airing, the one in which she’s hawking white jeans by crooning her version of “The Right Time” for a few cute friends during what looks like an impromptu backyard concert.

“That is so crazy,” she says, as images of swaying bodies flash across the screen, everyone decked out in summer Gap wear. The camera pans to her pals, then to her face, then to what looks like her swaying rear.

“That’s not my bum!” Stone screams.

“All these bum shots? They’re not mine. They’re, like, other girls. That’s not my bum, I promise,” she says, watching the screen with morbid fascination. “They totally make it like it is.”

This little editing trick genuinely freaks Stone out. Her face betrays the insecurity: Why would they do that? Why take the voice and not the rump? And is there something wrong with her rear end?

“I get really nervous. Apparently, I need a J.Lo bum or something,” she says.

Then to the publicists waiting outside she screams: “Bring in the implants, girls.”

The lesson: You might be young, willowy and talented, but show business can still rip you down. Chalk it up to one more thing the 18-year-old has had to learn during her wild ride from southern England.

Since winning a BBC talent contest at age 14, she has released two hit albums, snagged two Grammy nominations and serenaded President Bush. She calls Elton John and Tom Cruise friends, has been dubbed a diva by VH1 and gets tips on vocal spray from Sting.

But like the Gap ad, she concentrates on the flaws.

“When you step back and you look at it, it’s like, ‘Wow, that’s really cool that I’ve achieved this much.’ But I haven’t really achieved a lot, a lot, a lot compared to a lot of other singers,” she says.

“It does make me happy when I look at it. But, still, I’m very critical of myself in every situation, even if it’s something really good. I always find one note wrong. Always. Every single time.”

Fans apparently haven’t heard them. Stone’s first CD, “The Soul Sessions” -- a 10-song collection of little-known R&B; songs from the ‘60s and ‘70s -- zoomed up the charts in 2003, fueled by her reworking of the White Stripes’ “Fell in Love With a Girl.”

The album also brought disbelief in some corners -- that a white chick from rural England could sing like Aretha Franklin.

“Joss Stone just happened to wake up one morning with all this soul that had to come out. So people better not be thinking it’s a gimmick. It’s for real,” says Patti LaBelle, who has worked with and mentored Stone.

“She was born like that. She didn’t practice it. It just happened that she opened her mouth and a big black woman comes out,” LaBelle says. “The girl can just sing.”