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.
Alexandra continued: “Fast forward to Kate’s sapphire earrings, it is believed that of one of these pairs of earrings which Diana had.
“A part of them was remodelled into a pair of single diamond topped sapphire and diamond cluster earrings.
“Hanging from shepherd’s hooks, the round cut single diamonds look to be about 0.30cts each, with nine slightly larger 0.40pcts diamonds on each earring surrounding approximately 5ct each oval cut sapphires, most likely of Kashmir origin.”
The earrings match the Duchess of Cambridge’s ring and she has worn them regularly over the years.
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.