In particular, the royal would often wear sapphires and had a number of pieces that complemented her engagement ring.
Speaking to Express.co.uk, Alexandra Michell, Gemologist at Prestige Pawnbrokers of Channel 4’s Posh Pawn, commented on Diana’s collection.
The expert highlighted an “important” pair of sapphire earrings of Diana’s which have since been worn by the Duchess of Cambridge.
She said: “Diana had a lot of sapphire pieces. One of the most important pieces was a suite given to her by the Saudi Royal Family as a wedding gift in the late 80s.
“Sapphires were the coloured stone of choice so that Diana could wear these pieces to match her engagement ring. It has been rumoured that of these pieces, a pair of sapphire and diamond earrings were made, however this is only a theory.”
In more recent years Kate has been seen wearing the earrings for various events.
The drop earrings feature a small central sapphire surrounded by a number of diamonds.
While they look to be the same earrings, they seem to have been remodelled by the 39-year-old.
Not only are they stunning to look at, but the expert explained they could be worth a small fortune.
Alexandra concluded: “These make a regular appearance in Kate’s rotating jewellery collection, most certainly as they go perfectly, and as intended, with her engagement ring.
“I estimate these to fetch at auction in excess of £200,000.”
When wearing the earrings, Princess Diana would often pair them with her engagement ring and a matching sapphire and diamond necklace.
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The royal line of succession – who outranks who?
The line of succession to the British throne dictates the order in which each member of the Royal Family would ascend to the throne.
It is also seen as a ranking of importance with the head of the line, the Queen, taking the place of ruler.
Older children come before younger children. Traditionally boys came before girls, but this law was changed on 26 March 2015 before the birth of Prince William’s first child.
Incredibly, Catholics are still excluded from the line of succession, as are children born outside of wedlock.
The royals, who usually stick to a strict protocol when appearing in public, often arrive at events in ascending order of importance, with the most important royal arriving last.
Prince Charles, 72, is currently first-in-line to the British throne, followed by Prince William, 38, his oldest son.
Then comes Prince William’s children, George, seven, Charlotte, five, and Louis, two, and they are followed by Prince Harry, 36. Prince Harry is succeeded by his son Archie Harrison, born in May 2019.