Britain's Princess Eugenie opens up about her engagement to longtime boyfriend Jack Brooksbank.

The Queen's granddaughter shared his proposal was a "complete surprise," even though they have been dating for the past seven years.

Talking to BBC's The One Show, Princess Eugenie recalled how earlier this month, while in front of a volcano as the sun was setting in Nicaragua, Brooksbank went down on one knee and popped the question. They were looking over a beautifully sunlit lake when it happened.

"It was so beautiful," gushed the Princess of York. "The light was just a special light I had never seen."

Princess Eugenie recalls saying, "this is an incredible moment," just before the love of her life asked her to marry him, making the moment much more unforgettable.

The princess explained that while she always knew he was the one, she did not expect him to propose when he did. She thinks, however, that it was the "perfect moment."

"I was over the moon," said the eighth-in-line to the throne. "We couldn't be happier. We knew it was going to end up this way."

In the interview, the 27-year-old royalty proudly displayed her engagement ring, designed with a rare pink-orange padparadscha sapphire and surrounded by diamonds. Apparently, though, Brooksbank did not have a ring with him when he proposed. He said he knew Princess Eugenie would want to take part in its design.

According to 31-year-old Brooksbank, he already found a ring in a jewelers before he proposed. When they came back from Nicaragua, they decided to add flare to the sapphire ring by putting diamonds around it. His favorite thing about it is how it changes color depending on the angle, "which is what I think of Eugenie, that she changes color and is just amazing."

Princess Eugenie and Brooksbank will wed later this year at Windsor Castle's St. George's Chapel, the same venue of Prince Harry and Meghan Markle's wedding in May.