Kat Von D: Jesse James and I 'didn't break up'

Kat Von D and Jesse James are still going strong.

She recently fueled split rumors when she stepped out with ex Nikki Sixx at an Oct. 5 concert.

"I'm not dating Nikki," she told USA Today Tuesday afternoon while signing copies of her new book, "The Tattoo Chronicles." "We didn't get back together. Jesse and I didn't break up."

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The "L.A. Ink" star, 28, is proud of her relationship with the West Coast Choppers CEO, 41, who famously cheated on Sandra Bullock.

"I've known Jesse for a long time, since I was 22-years old," she says. "I think he's probably one of the most kind-hearted, intelligent human beings."

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At the book signing, Von D was sporting a sparkly diamond rock.

She wouldn't say if it's an engagement ring.

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"I don't know if I really feel comfortable talking about it," she said, adding that it was "from the 1900s ... It's been an addition to all the rest of my jewelry and my Victorian collection. They don't make things like this anymore. There's no more craftsmanship in a lot of things."