It seems like only yesterday—okay, maybe it was more like the 15th century, during the Spanish Inquisition—that having someone thrust hot rocks between your toes was considered a bad thing. How times change! In the past year or so, stone massage—a technique with ancient roots that involves rubbing superheated river stones over oiled skin—has become the hottest spa trend since aromatherapy and standard fare everywhere from Elizabeth Arden in Manhattan to the Golden Door in San Marcos, Calif. That's no surprise to hot-stone pioneer Carla Ciuffo, 41, whose Stone Spa in New York City (Gwyneth Paltrow and supermodel Christy Turlington are clients) was the first to focus exclusively on the treatment. The secret, Ciuffo says, is the heat: It allows masseurs "to go deeper into the muscle in a much less invasive way than traditional massage."

For her popular 70-minute Full Body Stone ($120), which designer Donna Karan says "reminds me of being on the beach and walking on the hot sand and stones," Ciuffo uses an array of smooth basalt rocks marinating in a 125° F to 135° F water bath, choosing those that fit specific muscle contours to massage the body from scalp to feet. (High iron content allows the rocks to stay hot for up to three minutes; when they cool, she replaces them.) She also targets "universal areas of tension" by placing warm stones under the neck, on the stomach and in the hands. "I've had almost every kind of massage," says client Fran Finkelstein, a 37-year-old Manhattan homemaker. "But once I went to Stone Spa I won't go anywhere else."

Ciuffo and her business partner Adam Schwartz, 27, make sure their clients don't have to. Stone Spa offers 11 stone massages, including Hot Stone Reflexology, which claims to "open blocked energy pathways" by massaging pressure points on the feet. While some are dubious about the benefits of reflexology, hot-stone therapy itself—used thousands of years ago by the Chinese to treat rheumatism and by Native Americans in sweat lodges—really works, says Elliot Greene, former president of the American Massage Therapy Association: "Heat increases circulation, making muscles more flexible."

Ciuffo seems to have been born for the job. Growing up on Long Island as the middle daughter of Loretta, 69, a homemaker, and dentist Armand, who died in 1997, she "always had an incredibly calming effect on those around her," recalls sister Roberta, 36, executive director of the Nashville Institute for the Arts. After graduating from high school in 1975, Ciuffo "floated around" several jobs in Manhattan, finally enrolling at the Desert Institute of the Healing Arts in Tucson in 1993 because, simply, "People always told me I had a great touch."

Introduced to stone massage in a workshop there, she immediately gravitated to it. "My father used to do a lot of gem sculpture," she explains, "so I've always been very attracted to stones." Ciuffo, who subsequently opened a private stone-massage practice, returned to New York in 1997 for her father's funeral and decided to stay. "Nobody was using stones out here. I just knew this was going to work."

A year and half later, her seven-masseur spa is thriving. This month, Ciuffo is launching a line of creams, scrubs and other skin-care products to be sold at the spa, and she plans to open a small spa-hotel in Long Island's tony Hamptons in April. Thanks to all that activity, Ciuffo, who was divorced in 1992, confesses she rarely has time to relax at the two-bedroom Long Beach house she shares with her 65-lb. bulldog Chester. "The spa," she says, "has become my baby, lover—everything."

Ting Yu in New York City