The collection included a custom bracelet, ring and earrings.
The classic set was made from white gold and diamonds and has an estimated cost of £60,000.
Kate appeared to be given the set shortly after her wedding, head of bespoke at 77 Diamonds Anna Byers explained.
“After her wedding to Prince William, Prince Charles gave his new daughter-in-law a set of matching yellow and white gold pieces,” she told Express.co.uk.
“This included a ring, bracelet and a pair of drop earrings she has since worn on several occasions.
“They are in an Art Deco style and seem to be custom made for Kate.
“Judging from the images, I estimate the value of these earrings to be £15,000 and the bracelet to be £45,000.”
If Prince Charles did give the gift so soon after her wedding, it is like that he was trying to welcome her into the family.
“The earrings feature two round diamond clusters almost in a flower shape,” the expert explained.
“The central diamond has a yellow hue, bridged by three horizontal baguette diamonds set in white gold.
“The bracelet has a repeating diamond cluster and baguette pattern bordered by two rows of diamonds, with the central diamond again seeming to have a yellow hue. The ring has a double diamond cluster.”
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How did Kate Middleton become a royal?
Kate Middleton, or Catherine, Duchess of Cambridge, was born on 9 January 1982 at the Royal Berkshire Hospital, Reading, England.
She was born to Michael and Carole Middleton, a former flight dispatcher and air hostess. The couple founded a party supplies company, Party Pieces, in 1987 – now estimated to be worth £30 million.
Kate has a younger sister Pippa Matthews, 34, and a younger brother James Middleton, 31.
Kate and her family moved to Amman, Jordan, in 1984, where the future Duchess was educated at an English-speaking nursery school.
After moving back to Berkshire the family sent Kate to private school, St Andrews School. She went on to briefly study at Downe House before moving onto Marlborough College where she boarded.
For university the young Kate attended the University of St Andrews in Fife, Scotland. Here she was awarded an undergraduate MA (2:1 Hons) in history of art.
Relationship with Prince William
Kate met Prince William when they were both studying at St Andrews, and both living in St Salvator’s Hall. Famously, William reportedly took a fancy to Kate after she wore a see-through dress during a fashion show.
In 2003 the couple began dating and lived together during their second year of university.
The couple split in April 2007, however, in October they were back together.
Prince William proposed to Kate Middleton with his late mother Princess Diana’s engagement ring in October 2010. The couple were holidaying in Kenya at the time.
On 29 April 2011 they married at Westminster Abbey with a whopping 26 million watching the event live.
Kate wore an Alexander McQueen dress worth a reported £250,000 on the big day.
Kate assumed the title “Her Royal Highness The Duchess of Cambridge” and also became the Duchess of Cambridge on the day.