Kate Middleton has worn an iconic emerald and diamond choker at the 2022 Earthshot Prize awards which used to belong to Princess Diana.
She showed off her green credentials at Prince William 's award ceremony that honoured environmental pioneers with a rented gown.
The Princess of Wales dazzled on the green carpet with her dress of the same hue as five innovative ideas that William hopes will help repair the planet were celebrated and awarded £1 million in prize money to scale up their projects.
And along with Kate’s green outfit, including a Solace London dress, was a famous piece of jewellery that was once owned by Diana.
The emerald and diamond choker had been used as a headband by Diana during a 1985 tour of Australia with her then husband Prince Charles.
She wore it at a gala dinner dance in Melbourne with legend saying that she settled on it as a headband after being unable to pull it down to her neck.
The emerald and diamond choker was originally gifted to Queen Mary in 1911 by the Ladies of India and then passed on to Diana by Queen Elizabeth when she married Charles - in a lifetime loan.
The Earthshot Prize Awards, staged this year in Boston, is one of the highlights of the Prince of Wales' official calendar and has been dubbed the future King's "World Cup" moment by Hannah Jones, the Earthshot Prize's chief executive officer.
Celebrities who walked the green carpet at the awards ceremony included Hollywood actor Rami Malek and David Beckham while artists performing on the night included Billie Eilish, Annie Lennox, Ellie Goulding and Beyonce proteges Chloe x Halle.
Malek, who presented the Fix Our Climate award, spelled out the environmental dilemma facing the planet before the ceremony, saying: "This is the greatest crisis that we are facing in our lifetime and it will probably be the greatest crisis that future generations are facing as well.
"But hopefully we can lessen that challenge for them by the actions we take right now.
"The innovation, the intelligent minds that are coming together to make changes and are being rewarded by the Earthshot Prize tonight will have a massive impact on what the world will look like."
Organisers of Earthshot have implemented a number of green policies, from encouraging guests to dress sustainably by wearing vintage clothing or recycling outfits for future use, to ensuring the plants and flowers on display are grown locally.
The awards ceremony was the culmination of a three-day visit by the royal couple to Boston which has been overshadowed by the race row that saw William's godmother Lady Susan Hussey resign as a royal aide after she repeatedly questioned a prominent black British-born domestic abuse charity boss about where she "really came from".
A trailer promoting the Duke and Duchess of Sussex's Netflix docu-series was released on Thursday, with the timing interpreted by some royal commentators as a snub to William and Kate.
Earlier, William met US president Joe Biden at the end of the royal's visit to John F Kennedy's Presidential Library and Museum, and held a 30-minute discussion which a Kensington Palace spokesman described as "warm, friendly and substantive".
The spokesman said Mr Biden was keen to learn about Earthshot and some of the stories from the finalists, including the Great Bubble Barrier, a 2022 finalist in the Revive Our Oceans category.
