"Justin," the actress, 46, says of fiancé Justin Theroux. "He's the best thing this decade."
The laid-back California girl, whose favorite item of clothing is a white tank top, tells PEOPLE these days the couple's fashion sense has "met a bit in the middle."
She fondly remembers the first time she met The Leftovers star while on the set of 2008 comedy Tropic Thunder in Hawaii.
"He was wearing black, black, black and I started to sweat just looking at him."
But the Aveeno spokeswoman says when it comes to engagement rings, her fiancé was spot-on.
"I just think it's so beautiful," she says of her sparkler. "I love it because he picked it, put it into a setting and it's simple."
"He's got a lot of hardware," says Aniston. "He wears a chain. He has a gold chunky ring. When we get married he will be wearing his ring. It just won't say Justin anymore," she says of the ring he currently wears, adding that perhaps instead it will say Jen "on the inside."
"It will be good," she says.
For more on PEOPLE's exclusive interview with Jennifer Aniston, check out this week's issue, on newsstands Friday