“I was impressed,” she tells PEOPLE of fiancé Justin Theroux‘s final choice. “I had no idea, and I had no idea what I wanted. He just knows what I like.”
Theroux “worked with the girls that I have worked with for years and years and years, so he kind of was picking the specialists’ brains,” Aniston shares. “He kept it within a very small circle of people. It was one of the sneakiest jobs I’ve ever seen, actually.”
And that left the actress, who is the new face and co-owner of Living Proof hair products, doubly impressed.
“It’s hard to pull one over on me,” she says, “where I’m not like, ‘Hmm, you’re acting really strange.’ It was … a very covert operation.” For more of our exclusive interview with Aniston, pick up the latest issue of PEOPLE, on newsstands now.
–Reporting by Julie Jordan