CNN  — 

Catherine, Princess of Wales, delighted at the 2022 Earthshot Prize awards Friday evening, showcasing her sustainable style in a rented gown and accessorizing with an emerald choker once famously worn by her late mother-in-law, Diana.

The emerald and diamond, art deco-style choker was a firm favorite of the late Diana, Princess of Wales, who daringly once wore it across her forehead as a headband during a 1985 tour of Australia with her then-husband Prince Charles. The piece of jewelry had been loaned to Diana by Queen Elizabeth II.

Kate paired the choker with a vibrant green off-the-shoulder Solace London gown rented for £74 ($90) from online platform HURR for the grand finale of a three-day royal trip to the US.

Prince William founded the Earthshot Prize back in 2020 in the hope of harnessing the world’s smartest minds to confront some of the most pressing environmental challenges facing humanity. Each year for the next decade, five winners will receive £1 million (around $1.12 million) to scale up their creative solutions.

The event staged this year in Boston was one of the highlights of the Prince of Wales’ calendar and had been dubbed the future King’s “World Cup” moment by Hannah Jones, the prize’s chief executive officer.

Speaking during the ceremony, William said: “I believe that the Earthshot solutions you have seen this evening prove we can overcome our planet’s greatest challenges. And by supporting and scaling them we can change our future.

“Alongside tonight’s winners and finalists, and those to be discovered over the years to come, it’s my hope the Earthshot legacy will continue to grow, helping our communities and our planet to thrive.”

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Britain's Prince William and Catherine, Princess of Wales, arrive for the Earthshot Prize awards at the MGM Music Hall in Boston, Massachusetts on Friday, December 2.
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Britain's Prince William and Catherine, Princess of Wales, chat with actor Rami Malek on Friday.
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Britain's Prince William shakes hands with US President Joe Biden in Boston on Friday. The two men shared "warm memories" of William's grandmother, the late Queen Elizabeth II, according to Kensington Palace.
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Prince William visits the John F. Kennedy Presidential Library and Museum alongside Kennedy's daughter, Caroline, on Friday.
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Catherine, Princess of Wales, signs a visitors book Friday while visiting the Center on the Developing Child at Harvard University.
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William and Kate speak with Boston Mayor Michelle Wu, third from left, and the Rev. Mariama White-Hammond as they visit east Boston to see the changing face of the city's shoreline on Thursday, December 1.
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Henry Dynov-Teixeira, 8, presents flowers to the royal couple during their visit Thursday to Greentown Labs in Somerville, Massachusetts.
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William and Kate learn more about climate innovations during their visit to Greentown Labs on Thursday.
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William and Kate greet a crowd in Chelsea, Massachusetts, on Thursday.
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Kate talks to a child Thursday while visiting Roca, a nonprofit organization.
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The royal couple watches an NBA game on Wednesday.
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William and Kate are joined by Wu and Massachusetts Gov.-elect Maura Healey as they kick off Earthshot celebrations on Wednesday. With the push of a button, they lit the civic building and other landmarks in green.
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A Boston subway station is illuminated green following Wednesday's lighting ceremony.
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William and Kate arrive at Logan International Airport in Boston on Wednesday.
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A Kensington Palace spokesperson told CNN the couple were eager for more time in Boston so they could get to know communities and learn about the climate-related challenges facing the coastal city.
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People in Boston await the royal couple's arrival at City Hall Plaza on Wednesday.

Sustainability was considered by Earthshot organizers in almost every aspect of the night. In a bid to make the occasion as eco-conscious as possible, all food served was plant-based and single-use plastic was banned, guests were transported to the venue in electric or hybrid vehicles, and a focus was put on hiring local crews and equipment.

Like Kate’s wardrobe choices, those hitting the green carpet were encouraged to dress in vintage ensembles or wear outfits they would recycle in the future.

Meanwhile, the recycled green carpet – which had previously been used at the inaugural awards in London last year – was adorned with plants grown within 100 miles of the venue which would be donated to community organizations following the glitzy event.

Celebrities at the awards ceremony included Hollywood actor Rami Malek and former England football captain David Beckham while artists performing on the night included Annie Lennox, Ellie Goulding and Beyoncé proteges Chloe x Halle.

David L. Ryan/Pool/The Boston Globe/AP
Prince William and Kate chat with actor Rami Malek at the awards Friday.

Chatting with CNN before the event, Malek commended William launching the prize and creating a positive approach to tackling the climate crisis.

“It’s extraordinarily inspiring. He is finding answers and the £1 million that are given to these five people, these five organizations, is something that keeps us from looking at the gloom and doom and the pessimism of it all, and looking toward the future of what we can come to do because when we put our ideas together, we can do extraordinary things,” said the 41-year-old “Bohemian Rhapsody” star who later presented the Fix Our Climate award.

The awards ceremony capped a challenging visit by the royal couple to Boston, which has been overshadowed by the race controversy that saw a woman identified as William’s godmother Susan Hussey in British media reports resign as a royal aide after she repeatedly questioned a prominent Black British-born domestic abuse charity boss about where she “really came from.”

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CNN’s Carolyn Sung contributed to this report.