When the conversation turns to jewelry in the 1955 Alfred Hitchcock film “To Catch a Thief,” a resisting Grace Kelly tells flirty Cary Grant, “I don’t like cold things touching my skin.”

Grant replies, “Why don’t you invent some hot diamonds?”

OK, so the line isn’t Grant at his smoothest, but the Hot Diamonds jewelry line – distributed throughout the United States from a leased building in a Belfast business park – is scoring big with 25- to 35-year-olds.

Prismax, a business launched by Camden’s Tim Lawrence, began importing the Hot Diamonds line from England in late 2002, and last year his sales approached $9 million. Lawrence expects the growth to continue, and is talking about buying the building, which formerly housed Harborside Graphics, and expanding it.

Who knows whether Grace Kelly would have liked Hot Diamonds jewelry, but rocker Sheryl Crow does. A letter from Crow, framed in the company’s waiting room, reads: “Hot Diamonds is a gorgeous product. I am a huge fan of its versatility.”

Chief Marketing Officer Shawn Stockman believes the company’s success in the United States, which accounts for 45 percent of the world’s jewelry market, has more to do with its style, its pricing niche and clever marketing.

First, the style.

All of the jewelry is made of sterling silver, covered in rhodium.

“It gives it the really high-polished look,” Stockman said of the rhodium, as well as permanently preventing tarnishing. “It gives it the sheen of white gold.”

The necklaces, chains, pins, bracelets, earrings, watches and rings are not flashy, but modern looking.

“They’re very contemporary designs,” he said, yet “not a bling-bling kind of thing” favored by rappers and their imitators. Rather, the products are understated yet sexy, hip but leaning toward classic, artsy yet not shocking.

One can imagine, Stockman said, the pieces worn by a young woman to her first office job, and later that night at a club.

Almost every piece features a diamond, albeit a small one.

With much of the Hot Diamonds line retailing at around $100, the price is right, Stockman said.

“It’s entry-level diamond jewelry,” he said.

Jewelry store owners often are content to sell one pearl necklace a year for $10,000, so convincing them to carry products with a price tag a fraction of that is difficult, Lawrence and Stockman said. But they are making headway in persuading store owners that by carrying affordable jewelry, the stores build relationships with young customers that will last through wedding ring and anniversary earring purchases.

And though Hot Diamonds is affordable, the products don’t look cheap.

“The reason the product sells is it looks really expensive,” Stockman said.

Each piece is sold in a highly polished wooden box, bound to elicit “oohs” and “aahs” from those receiving the items as gifts.

Stockman imagines a college-age young man purchasing earrings, or a watch, or maybe even a ring for that serious girlfriend, and coming off as grown-up, sophisticated and generous with his choice.

“It’s a way for him to give her a diamond ring that’s not ‘the’ diamond ring,” he said.

Another imagined customer is the bride who wants to purchase something classy and elegant for her bridesmaids without going bankrupt.

The marketing of Hot Diamonds may not seem clever so much as obvious. Catalogs, magazine ad slicks, postcards and store posters feature minimally clad women cavorting for the camera, leaning back seductively in chairs and lying on beds.

Stockman chuckles as he points to another picture of a bare-chested man whose head is cropped off to put his six-pack abs in the center of the image. Around the office, the model is known as “torso man.” A video version of the ad shown at a trade show, Stockman said, panned down from the man’s neck, to his chest, abs, and lower, eliciting more than one audible “Oh, no!” as it seemed the commercial was about to cross a line.

“We’re trying to become a little more wholesome,” Stockman said. Some of the ads were rejected by stores in the South.

But the message is clear. This isn’t your mom and dad’s jewelry. And you don’t have to wait until your hair is gray to afford your own.

“It’s an image-driven product,” he said, communicating “a young, sort of fancy-free concept.”

Lawrence, who was born in England but grew up in the Australian island province of Tasmania, is a burly, bearded, low-key sort who seems to take the company’s success in stride. At 56, he has seen success in a variety of fields, including working as a guide for hikers on Alaska’s Mount McKinley.

He and his wife started and sold some gift stores in Massachusetts, then moved to Maine and opened the Ducktrap Trading Company store in Camden. On the side, Lawrence had been managing English jewelry sales in the States for a few years.

Familiar with the Hot Diamonds brand when the English parent company asked him to oversee distribution in the colony, Lawrence instead said he would buy the exclusive rights to sell the product here.

“I said, ‘Send me a bunch of stuff. I’m going to try it out on 10 jewelers,'” he recalled. In three weeks in the fall of 2002, Lawrence had $150,000 in sales booked.

In 2003, sales were $4.8 million, and then nearly doubled in 2004.

While it may seem that Lawrence has stumbled onto a gold mine, Stockman speaks with awe about the bold moves Lawrence made early on, moves that defied conventional business logic. Instead of quietly building the line’s visibility in trade magazines, Lawrence sank $200,000 into advertising in magazines such as Cosmopolitan and Elle.

And the company does a lot more than open boxes from England and re-address them to stores around the United States.

The jewelry is designed by the Hot Diamonds company in England and manufactured in China. The products are unpacked, inspected, tagged and carefully placed in boxes at the Belfast facility, where 40 people are employed.

After beginning with commission-only salespeople who sold other lines as well, the business now is hiring sales representatives who deal exclusively with Hot Diamonds jewelry, supplying some 2,000 stores.

Hot Diamonds jewelry is featured in the in-air catalogs of a dozen airlines. It’s also sold on 85 cruise ships.

Those sales account for less than 15 percent of the company’s total, but Stockman and Lawrence like the visibility it gives the product.

Hot Diamonds jewelry is sold in Maine at Day’s and G.M. Pollack, as well as at individually owned stores.