One hour after she announced her engagement to Liam Hemsworth, Miley Cyrus posed for the September cover of Marie Claire magazine. The 19-year-old actress looks cool and shophisticated in a light blue dress covered with giant gemstones.

The issue, which hits newsstands Aug. 14, delves into the details surrounding Miley's engagement to actor Liam Hemsworth, 22. She admits it was a "complete surprise" when he proposed at the California home they share. She also says her parents Billy Ray and Tish had no idea about the proposal. So apparently, Liam didn't ask permission before popping the question.

"Life is too short not to be with the person you want to be with," Miley says to skeptics who think getting married at such a young age will lead to divorce. "I don’t really care about the wedding or the piece of paper as much as I do the promise we’ve made to each other. And we want to have a long engagement."

It seems that Liam is a little old fashioned because he picked out Miley's 3.5-carat engagement ring without her input. The vintage-inspired jewelry is handcrafted in 18-karat gold and is garnished with diamond floral patterns. It has an antique stone center that was handcut around 1880 or 1890.

"I had no input," Miley explains. "We’d been kind of talking about getting engaged…I saw it online at one point and thought it was really pretty…I just love that it’s old and has a story.  And I’m happy because it doesn’t look like anything else I wear."

Miley may be young, but she knows what she wants. "Liam and I have a really good relationship…neither of us is super-jealous.  We know each other and would never do anything to hurt each other," she insists.

Liam recently told Men's Health that Miley is "an extremely strong, intelligent, supportive person."