Princes William and Harry, who have reportedly been estranged for over a year, made a rare appearance together Thursday to honor their mother, the late Princess Diana.

William and Harry, the only children of Diana and Prince Charles, were both present as a much-anticipated statue of Princess Diana was installed in the Sunken Garden of Kensington Palace on July 1, which would have been Diana's 60th birthday.

"Today, on what would have been our Mother's 60th birthday, we remember her love, strength and character – qualities that made her a force for good around the world, changing countless lives for the better," the brothers shared in a joint statement. "Every day, we wish she were still with us, and our hope is that this statue will be seen forever as a symbol of her life and her legacy."

The princes also thanked the statue's sculptor, Ian Rank-Broadley, and the garden designer, Pip Morrison, for their "outstanding work" as well as shouted out "all those around the world who keep our mother's memory alive."

Also in attendance at the event were Diana's siblings: The Earl Spencer, The Lady Sarah McCorquodale and The Lady Jane Fellowes.

Not in attendance were the brothers' wives as well as their father, Prince Charles, and their grandmother, Queen Elizabeth.

The statue itself, which is 1.25 times life size and bronze, aims to "reflect the warmth, elegance and energy" of the late Princess of Wales and shows her surrounded by three children meant to represent "the universality and generational impact" of her work, according to Kensington Palace.

"The portrait and style of dress was based on the final period of her life as she gained confidence in her role as an ambassador for humanitarian causes and aims to convey her character and compassion," the palace continued.

The base of the statue features Diana's name and the date of its unveiling. In front of it is a paving stone engraved with an extract from the poem "The Measure of a Man."

The statue was commissioned by William, 39, and Harry, 36, in 2017 to mark the 20th anniversary of their mother's death.

Diana died in August 1997 after a car crash in the Pont D'Alma Bridge in Paris. William and Harry were 15 and 12, respectively, at the time.

"It has been 20 years since our mother's death and the time is right to recognize her positive impact in the UK and around the world with a permanent statue," the brothers said in a joint statement in 2017. "Our mother touched so many lives. We hope the statue will help all those who visit Kensington Palace to reflect on her life and legacy."

Just one year after the 20th anniversary of Diana's death, in 2018, Prince Harry wed his wife, Meghan, the Duchess of Sussex.

The couple, who now live in California, stepped down from their roles as senior, working members of the royal family last year amid family tensions that they went on to reveal in a tell-all interview with Oprah Winfrey in March.

In the interview, Harry described himself and William as being on "different paths."

"The relationship is space at the moment, and, you know, time heals all things, hopefully," Harry said. "I love William to bits. He's my brother. We've been through hell together, and we have a shared experience, but we were on different paths."

William and Harry grew up at Kensington Palace and Diana lived there until her death.

Harry and Meghan, who just welcomed their second child, a daughter named Lilibet Diana, at one point also lived in Kensington Palace near William and Kate, who still have their main residence there with their three children.

In 2019, Harry and Meghan moved from the palace to a new home in Windsor and also left the household they shared with William and Kate, a split that author Robert Lacey said was due to an "explosive argument" between the brothers.

Citing palace insiders, Lacey wrote in his new book, "Battle of Brothers," that Harry reportedly hung up the phone on William, who then went to address him in-person about the way Meghan was reportedly treating palace staff.

After the argument, William reportedly instructed a royal aide to "start the process of dividing their two households immediately," according to the book.

William and Harry's first in-person reunion in over a year happened in April, when the royal family came together for the funeral of the brothers' grandfather, Prince Philip.

Their wives, Kate and Meghan, have not seen each other in person in over a year.

Many see today's event as a chance for the brothers to bridge the gap between them.

"I think there's been a lot of hope that an event like this would bring the brothers back together, and it's certainly true that their mother's memory and honoring her memory is pretty much one of the only things that really unites them right now," Victoria Murphy, ABC News royal contributor, said.

Robert Jobson, another ABC News royal contributor, said he hopes William and Harry will be able to reconnect, adding that the presence of Diana's sisters and close members of the family might help.

"Just standing there and looking at that statue ... in the Sunken Gardens where they used to play as kids with her looking over them, maybe that just might be the catalyst to start the end to this rift," Jobson added.

While he said the relationship between the brothers is still "extremely complicated," ABC News royal contributor Omid Scobie said he understands "it is still a case of distance" and "they're simply not talking at the moment."

"This is really going to be the first time where they have a proper opportunity to chat to each other," Scobie said. "And maybe being here in the presence of the memory of their mother will be a reminder of the importance of love and family."