Tina Collins is edgy. There's a flutter in her smile. She can talk of little else but the princess of Wales.

"She's going to be here! In the same city as me!" says the 20-year-old Collins, her blue eyes gleaming like a diamond tiara, her voice twanging of her native Tennessee.

Dominating the dining area of her Alexandria apartment, regally winsome in a gilded frame, is Diana -- pastel on poster board. Collins is rather fuller of figure than the thin, rich princess. But she is Di-like in her blondness, Di-like in her coiffure and Di-like in her navy suit -- actually a uniform for greeting passengers at National Airport's Butler Aviation.

"I don't know if they'll let me off work to see her," she muses. "If I could only be sure of meeting her, I'd just quit. I can always find another job." She fidgets with a prized videotape cassette of royal wedding highlights. "Who knows how much I've watched it? -- something like 250 times.

"Obsessed?" asks Collins, with a few days to go before the royal couple hit town. "No, that's a strong word. It makes me sound deranged. I'm not deranged. I'm normal. I wouldn't harm anybody."

Indeed, the outward evidence suggests she's normality incarnate. She holds down a responsible job; happily shares her apartment with a sorority sister from student days at George Mason University; has a steady boyfriend, a George Mason senior who works in Hechinger's lumber department; likes cuddly stuffed animals. But then there's the portrait of Diana -- executed on commission by a sidewalk artist in Gatlinburg, Tenn. And, atop the dining table, a pair of foot-high dolls of Charles and Diana in wedding regalia.

"I ordered them from the Sears catalogue, but I didn't get the glass case," she apologizes. "Maybe I will, though -- they're getting so dusty."

But it is in the privacy of her bedroom that Collins gives her Di-mania full reign.

The wall facing her bed is a veritable shrine -- each photo of Di (and a few of Chuck) snipped from a commemorative calendar and hung in a yellow frame. "I got the frames at K mart -- kind of cheap to put the princess in, but that's all I can afford." A nearby set of shelves is brimming with lovingly laminated Diana scrapbooks, well-thumbed Diana picture books, Diana magazines and supermarket tabloids ("I just buy them for the pictures, I don't read them"), Diana paper-doll books, a leather-bound volume of Diana postage stamps, even a "Color Me Princess" coloring book.

Collins has carefully crayoned several of the pages, doing an especially nice job -- in yet another wedding scene -- of capturing the sea-foam green in the Queen Mum's fuzzy hat.

A second set of shelves displays a commemorative candy box, Wedgwood tea plates, a coffee mug, an embossed vinyl eyeglass case, key chains, a thimble and -- barely visible behind a roll of bathroom tissue -- a photo of Collins' boyfriend. Says 22-year-old David Birdsall of his girlfriend's enthusiasm: "It's really not as bad as it looks -- as far as I can tell."

"I think it's pretty interesting," says her roommate, Jennifer Dixon, who only learned of the hobby when they moved in together two months ago. "I guess you could say I was surprised when I saw her whole wall covered with these pictures."

"I think it's like a Cinderella story to Tina," says Lavinda Collins, her mother, a willing accomplice in her daughter's avocation who is always on the lookout for Diana-iana.

As for the Di fan herself, she says, "So many people nowadays idolize hard-rock groups, it's just nice to have such a fresh face to admire . . . I'd kill to have skin like that. And I just love her accent."

Collins was growing up in Harrogate, Tenn., a quiet burg where her parents run a printing business, when Diana Spencer entered her life five years ago. After reading about Diana's sudden engagement ("I think it was in Vogue"), she fell for her head over heels and has remained in that attitude ever since.

"I guess it was the fairy tale that got to me," she says. "It was just like a dream. All little girls dream of being a princess and marrying a prince, and I do dream a lot. I even saw myself marrying Prince Charles and living that type of a life style. I'd love her life style, if just for a day. I'd love to have her clothes and jewelry."

What about having the queen for a mother-in-law?

"That's wouldn't be bad at all."

And being part of the royal family?

"I can get along with anyone, if they can get along with me."

Even Princess Anne?

"Well, like everyone, I have family members that I don't particularly care for, and we've made it okay so far."

She adds, "I know I'm never going to be a princess. But the important thing to me is where Diana came from. She was titled, but she was obscure, just like me. I'm obscure. She was like just about any teen-ager graduating from school and getting her life started. She had a job, just like me. She had roommates, just like me. We're both the same sign -- Cancer. We both have small cars. Mine is a blue Nissan, hers was a red Metro -- I don't like red cars, red's a dangerous color. She loves to shop, and so do I -- though I don't think she'd ever pop down to Shopper's Warehouse for groceries.

"And," Collins says, her eyes going somewhat moony, "she gave it all up for the man she loved. And she wasn't only giving up the freedom of being a bachelorette. She was giving up an entire life style."

Not surprisingly, she is quick to protect her princess from any and all critics. "If Princess Di is listening to her Sony Walkman, what's the matter with that? I listen to my music. She's not dumb. She's not dumb at all. Could anyone carry herself around the way she does and be stupid? She has everyone in the world charmed."

Collins says she doesn't know any other fans of Di, nor is she hoping to meet any -- Di-mania being a solitary pursuit.

"I don't think it would be proper etiquette to start a Diana fan club," she says. "That just isn't done."