Jennifer Aniston gushed about fiance Justin Theroux during a Details magazine dinner in his honor in West Hollywood on Tuesday, July 15 Credit: Matt Sayles/Invision for DETAILS/AP Images

Tight-lipped no more! Jennifer Aniston has kept quite mum about husband-to-be Justin Theroux, but she couldn't help gushing during a dinner in his honor earlier this week. The Horrible Bosses 2 actress went into juicy detail about what she loves about her longtime beau while attending a bash hosted by Details magazine at the Sunset Tower Hotel in West Hollywood on Tuesday, July 15.

"He's so graceful and utterly kind and golden," Aniston, 45, told Women's Wear Daily of Theroux, the man of the hour. (The Leftovers actor, 42, landed the cover of Details' August issue.)

"It is amazing. He's just so beautiful and handsome to me, and I love that his eyeballs are so beautifully captured because those eyes just knock me out every day," she continued, referring to his cover. "He just gets better every year."

Taking it one step further, Aniston described her smoldering fiance as a "lost gem" in the sand. "He's just always been there and been brilliant, and now this is just in a different light," she said.

The couple—who got engaged in August 2012—were joined at the event by Aniston's BFF Courteney Cox and her new fiance, Snow Patrol rocker Johnny McDaid. "There's no better cover boy than Justin Theroux," Cox added to WWD. "He's so handsome and cool."