Hours after Emma Beacom pulled on the first of a dozen dresses she thought might be perfect for the Gaithersburg High School prom, she spoke in The Voice.

It was the high-pitched, hopeful sound of a 17-year-old who thought she had just ended her search with one look in the mirror.

"Do you like it?" she asked her friends, staring at the black strapless gown. "Tell me seriously."

The word "prom" should be a verb in some teen-age circles. To go to one seems synonymous with the word "buy." Such as: to buy a dress, to rent a tux, to buy a corsage, to get a new pair of earrings, and maybe even to rent a limo that will clinch the glitz.

First, however, comes shopping.

Emma and her friends found the first batch of prom dresses in a nook of the Saks Fifth Avenue store where garments come in size 3 and price tags come in three figures.

After one look, they knew they wouldn't have an easy time of it. Emma didn't want lace. Suzanne Roth, dark-haired and tiny, didn't want frills. Their taller buddies, Debbie Padan and Kim Noffsinger, didn't quite know what they wanted -- but they didn't think it could be any of the flouncy things that Saks had to offer.

"Everything's so Madonna-ish," said Debbie, looking at a white dress, cinch-waisted and strapless, that Emma held.

"I think it's neat," Emma said.

"Yeah, but you'll look like a pumpkin," Debbie said uncharitably.

The girls figured they'd each probably have to spend about $200 for the big night of June 1 -- including the dress, shoes, a purse, maybe some sparkly hose and big, flashy earrings. Keeping the lid on costs would be no small feat, what with the right kind of dresses -- from TD4 (to die for, of course) -- costing upwards of $150.

"But I don't really care what I have to pay," Emma said, pushing the white dress back on the rack. "As long as it's nice."

There's no easy way to fit four girls in one dressing room. But that seems to be half the charm of buying a prom dress. Zip. Zip. Turn and stare.

"This is squishing me to death," Kim groaned from within the folds of a tight-bodiced, full-skirted whirl of white acetate, nylon and rayon.

"Great, this makes me look flat -- just what I need," Debbie wailed.

"I like strapless," Suzanne said, a little smile perking at the corners of her mouth. "It's going to be hot."

No mothers were there. No one could tell them what was too short, too low-cut, too daring or too wild.

"My mom," Debbie said, grinning, "would just get in the way."

Saks behind them, Mazza Gallerie came next. The girls had come south to Friendship Heights to try to buy something no one else would be wearing. But their exacting tastes began to get in the way.

At Neiman-Marcus, Emma found the black net dress, daubed with rhinestones and flirtatious with ruffles. Kim grabbed a gray-and-pink number that could be made tight at the waist.

One look in the three-way mirror and Emma looked to her friends for confirmation. Was this THE dress?

Kim, turning and twisting in front of the mirror, decided for her the style was good, but not the color. She would continue looking for a more perfect dress.

Emma turned back to the mirror.

"Girls who come here are looking for something more sophisticated," the saleswoman said to no one in particular. "They're young, they're sexy, they're looking for a little more."

Emma put the black dress on hold.

Say prom to women who remember a time when strapless dresses were in vogue and many conjure up a high school gym, corsages that kept slipping down taffeta dresses, and the stupid pictures that parents snapped before and after dates arrived.

Today it seems a bit more elaborate.

Teachers at Gaithersburg recall the kid last year who rented a Silver Cloud Rolls Royce -- equipped with television and wet bar -- to impress his girl. And then there was the other guy who saved money all year to rent a limousine and drive his date around town after the dance.

About half of the 1,000 students in the junior and senior classes at Gaithersburg are planning to attend the $25-a-couple joint dance at the Holiday Inn in Bethesda the first Saturday in June. Many plan to go to dinner before the dance begins at 9 p.m. and hit the nightclubs afterward, students said.

The county and the School Board plan to combat any problems of drinking this year by setting up a hot line telephone for students to call if they feel they shouldn't get behind the wheel. Free rides will be provided for those in need.

The shopping expedition's last stop was the Neiman-Marcus jewelry counter. By late afternoon, no dresses had been purchased and no one could stand the thought of looking through another rack of clothes.

Emma sidled up to the jewelry tray and found a pair of earrings, heavy with glass and black beads. She put one to her ear and it sparkled. She held her head one way and it caught the light again. She turned her chin down and she knew they were perfect.

Then she saw the $65 price tag.

"No way," she said, flipping it back into the tray. "Even my dad wouldn't buy them for me."