Jennifer Aniston absolutely "loves the ring" that her fianc Justin Theroux proposed to her with.

The 43-year-old actress and the actor have been dating for around 15 months.

Jennifer and Justin became engaged on his 41st birthday last Friday.

Jennifer is impressed with the gorgeous piece of jewellery that her beau picked out for her.

"It's a huge emerald-cut [eight-carat] diamond," Jennifer's friend told Life & Style magazine. "It's a rectangle with tapered diamond baguettes on the sides. It's beautiful.

"Just after Jen got engaged, she called all her friends and told them about it. She was so happy and said she loves the ring. I think she was overwhelmed and overjoyed by the size and beauty of it!"

The couple began dating after they shot movie Wanderlust together and there are rumours they are planning to wed in Greece later on this year.

Jennifer and Brad Pitt tied the knot in 2000, but divorced five years later.

Before meeting Jennifer, Justin dated Heidi Bivens for 14 years before their relationship ended.