It took quite a while, but Nicky Hilton finally debuted her engagement ring, She Knows reported.

The hotel heiress took to her Instagram on Saturday to post a photo of her with her ring. The photo was from Hilton and her longtime boyfriend, James Rothschild's European vacation in August, when the banker asked Hilton to marry him.

In the Instagram photo, Hilton can be seen posing with her hair tucked behind her left ear and her left hand showed off her ring, while the Eiffel Tower stands in the background. The heiress captioned the photo with "#engagementmoon in Paris #FlashbackFriday."

A diamond expert gave E! News the breakdown on the massive bling, saying that the carat size looks to be between 6 to 8 carats and could be Royal Asscher cut. The expert pegs the ring to cost between $500,000 to $800,000.

The 30-year-old heiress and Rothschild, who is an heir to a European banking family, have been dating since 2011. Last summer, the couple went on a roadtrip all over Europe to celebrate their anniversary, and Rothschild reportedly proposed in Lake Como, Italy.

A source told US Weekly that Rothschild the "incredibly romantic and beautiful" proposal happened in the middle of Lake Como during a boat ride. Still, Rothschild reportedly first went to the United States to ask Hilton's parents approval before he asked the question.

The engaged couple remains tight-lipped about their wedding plans, but several news outlets revealed the Nicky's older sister, Paris, is already looking at houses in New York so she could be near her sister and help out with the wedding preparations.

The 33-year-old hotel heiress, who is currently based in Los Angeles, Calif., was reportedly hunting for penthouse apartments during her recent visit to the Big Apple, according to Page Six. Hilton was in town to support her younger sister during the launch of Nicky's book, "365 Style."

A source told the publication that Paris Hilton wants to spend more time in New York not only to help Nicky with her wedding, but also to spend time with her brother Barron, who also lives there.