The Stornoway team has already had exploration success, including the 2002 discovery of several promising prospects in Canada’s eastern Arctic territory of Nunavut. The result was the second staking rush in a decade, with Thomas leading the way rather than merely following. But the company has had nothing approaching a repeat of Diavik. Thomas is undaunted. “Ultimately, we’ll find another Diavik,” she says. “Given enough time and money, I know we will do it again. It’s not even an ‘if.’ It’s a matter of when.”

Eira Thomas was born in Calgary, Alberta, on November 20, 1968, to Grenville and his Canadian wife, Gail. The name Eira is Welsh for “snow,” reflecting the weather that day. The eldest of four children, Thomas spent her early years moving from one promising exploration venue to the next. The family was living in Yellowknife when she was born, but moved to Calgary, Wales, and Vancouver before Thomas was a teenager.

In other words, she comes by her interest in geology honestly. Her father remains one of the most revered explorers in Canada. “Gren has incredible goodwill in the north,” says Bob Bishop, editor of the Gold Mining Stock Report. “In Yellowknife, you’d think you’re walking around with God.” After graduating from high school with a tentative plan to head to the University of British Columbia the following fall, Thomas went up to Yellowknife for the summer. She very nearly stayed. “I had such a great time that I didn’t feel compelled to continue my education at that point,” she says.

Her mother was aghast. “She saw it as a bad omen—I was going to stay up north and never finish my education. And this would have been a total disaster,” says Thomas. Mother prevailed, winning her over with the idea that perhaps she’d be happier 2,750 miles away, at the University of Toronto. After starting out as a biology major, Thomas switched to geology in her second year. “But I didn’t know at the time it would be my life’s destiny,” she says.

By all accounts, Thomas has managed to keep a modicum of balance in her life. One of her closest friends, Mat Wilcox, says Thomas surprises her constantly. “We were up north, and Eira decides she’s going to adopt these sled dogs,” Wilcox says. “We didn’t have leashes, and they had diarrhea all over the plane, but she didn’t care.” Although she ended up selling the sled dogs, Thomas now has two of her own, both of them a mix of husky, wolf, and hound, with bright blue eyes. Thomas named them Melville and Hudson, after Nunavut’s Melville Peninsula and Hudson Bay.

Thomas’ previous pet, a sled dog named Thor, was briefly as famous as his owner. In the early days at Lac de Gras, Thor was spooked by gunfire and took off running, eventually making it all the way to Fipke’s camp some 60 miles away. Suspecting a ruse by Aber, Fipke’s people wouldn’t let Thomas pick him up at their camp, forcing her to fly all the way back to Yellowknife to retrieve him. The whole episode earned Thor the sobriquet Spy Dog of the North.

At the end of each day, Thomas retreats to a two-story hideaway sandwiched between mountains and water in the hills outside West Vancouver. Decorated with Inuit art, the house is sparsely but elegantly furnished. It has a jaw-dropping view across Howe Sound to Bowen Island, but its relative isolation from town would probably be unacceptable for most unmarried people.

But this is a woman who finds inspiration in the endless tundra of the north, who vacations from a life spent working in the Arctic by hiking up to one of the base stations at Everest—a woman who likes Sun Valley, Idaho, because of its remoteness and who recently bought a plot of land there after coming across it while vacationing with her dogs. (That trip, by the way, included a 20-mile ski-joring race—wearing skis and being pulled by her dogs—that she’d decided to train for on a whim.)

Thomas admits that she loves diamonds just as much as the next girl. She laughingly recounts the time that Harry Winston vice chairman Peter Schneirla allowed her and McLeod-Seltzer to try on all of the jewelry in the New York store. “Peter is an honorary member of our Tiara Club, which he’s quite happy about,” Thomas says. If owning actual Harry Winston jewelry is required for entry, Thomas has that covered: Her father recently bought her earrings and a watch.