Kate Middleton sent a meaningful message with her accessories during a surprise appearance with Prince William on Thursday, Sept. 10.

The Prince and Princess of Wales, both 44, joined sports stars at Hill Dickinson Stadium in Liverpool to help launch a new mental health guide as they marked World Suicide Prevention Day.

Prince William wrote the foreword to On Your Side: A Suicide Prevention Toolkit for People in Sport, which is aimed at helping people spot the warning signs and hold supportive conversations so they can intervene before a crisis point.

He also spoke at the event, telling the crowd, “Suicide remains one of the greatest challenges facing our society. Many people will have felt the impact of this personally. You will know families whose lives have been changed forever by loss. Today, we remember them. And we recommit ourselves to doing everything we can to prevent more families from experiencing that pain.

For the outing, William looked smart in a navy blue suit, while Kate donned a robin’s egg blue pantsuit. But it was her earrings that held a significant message related to the cause at hand.

Back in June 2023, the Princess of Wales visited the Maidenhead Rugby Club, where she met the club’s under-14s coach, Sarah Renton. Also a mother of three, Renton told Kate that she had lost her daughter, Issy Phipps, to suicide. Renton gifted the royal with a pair of “Issy Star” earrings that the late teen’s cousin made in tribute.

These earrings are still available for purchase, with $5 of every pair going to Brave Mind U.K., an organization that uses sports to support young people’s mental health.

Kate has been pictured wearing them during multiple mental health-related engagements, including when she and William hosted the Royal Foundation event, Exploring our Emotional Worlds, on World Mental Health Day in October 2023.

The earrings were a fitting tribute as Princess Kate and Prince William took part in a forum for young people at the Factory Works center in Birmingham, England, alongside BBC Radio 1 and the charity The Mix. There, the royal couple participated in mental health workshops, and Kate took to the podium to urge participants to come together to “build a brighter, more resilient future.”

The small gold stars were on display as Princess Kate addressed the crowd, saying, “Today, more people feel empowered to talk about their mental health than ever before. This is a major step forward.”

“William and I continue to be inspired to see young people, like you all here today, leading this charge – being particularly brave in having some of those conversations yourselves,” Kate continued. “As a generation, you value and talk more about your mental health than any before you – something we truly admire and applaud.”

Princess Kate’s necklace at Thursday’s event also had a special sentimental meaning.

For the outing, the mother of three once again donned her gold Laura Lombardi portrait necklace, which she wore just two days prior while dropping off her eldest son, Prince George, for his first day of Eton College.

The thick chain, which features interlocking links and an oversized toggle clasp, is a slightly larger and more modern piece for the Princess of Wales, who tends toward delicate thin chains.

Prince William and Princess Kate did extensive research on a new school for their eldest son. However, a source close to the family recently told PEOPLE, “George has always wanted to follow in his dad’s footsteps” when it came to attending the prestigious all-boys boarding school.

Upon their arrival, the trio was welcomed by the school’s headmaster and provost before going inside to help him settle into his new room.

“Eton was a much-needed haven for William,” royal biographer Sally Bedell Smith told PEOPLE. “It will give George a rigorous education that he will need for his role.”