Warren Buffett calls the CEOs who run his companies “All-Stars.”

The world’s most renowned investor picks his managers practically as well as his stocks. But branding the bosses of businesses owned by Berkshire Hathaway “All-Stars” may also be a clever people-management ploy on his part–to inject so much confidence in his people that they feel they must be the best…and duly pressured, they are.

At the recent Fortune Most Powerful Women Summit (where Buffett, one of the few male attendees, says, “For a guy who couldn’t get a date in high school, this is heaven”), he and two of his All-Stars clued us in on how he motivates.

One “All-Star” in attendance, Cathy Baron Tamraz, sold her company, Business Wire, to Buffett sight unseen, after speedy negotiations by phone, in 2006. The deal worked out well, because “if I had met her, I would have paid more,” Buffett said, calling the news-distribution service “a fabulously successful business.”

Tamraz suspects that Buffett has a psychology degree because, she said, “Warren makes us feel like we can do no wrong.” He’s no trained psychologist, but he may be as good as one. “It’s a very frightening thing to do to us,” Tamraz said. “We’re not going to sleep at night because we’re going to get it right every single day. It’s extraordinary.”

The other “All-Star” at the Summit: Susan Jacques, the CEO of Borsheims Fine Jewelry and Gifts in Omaha. Twenty-seven years ago, Buffett explained, Jacques arrived at Borsheims as a $4-an-hour clerk. He detected certain skills in this dynamic young woman from Zimbabwe, and 12 years later he made her CEO of the jewelery retailer. The promotion surprised many people, he admitted, but “she turned out to be a fabulous CEO.”

Jacques said that the best advice she’s gotten from Buffett comes in a memo that he sends to his 77 All-Stars every couple of years. Every memo includes some version of this message:

We can afford to lose money–even a lot of money. We cannot afford to lose reputation–even a shred of reputation. Let’s be sure that everything we do in business can be reported on the front page of a national newspaper in an article written by an unfriendly but intelligent reporter. In many areas, including acquisitions, Berkshire’s results have benefitted from its reputation, and we don’t want to do anything that in any way can tarnish it. Berkshire is ranked by Fortune as the second-most admired company in the world. It took us 43 years to get there, but we could lose it in 43 minutes.

“This is the mantra I use every day in both my personal and professional life,” Jacques said, noting three more pieces of wisdom from Buffett: “Think like an owner. Tell us bad news right away. And if you don’t know jewelery, know your jeweler.”

P.S. Buffett introduced a Summit session called Most Powerful Women in Small Business, which spotlighted a new program from Fortune and American  Express –where Buffett is the largest shareholder. We selected 10 extraordinary female entrepreneurs and brought them to the Summit. Stay tuned to Postcards for more about this new initiative.