BEFORE her passing in 1997, Princess Diana left instructions for the division of her glittering jewellery collection.
In a letter of wishes, the royal explained that she wanted it to be given to her two sons in the hope they'd one day pass it onto their future wives.
Her wishes came true in 2010, when Prince William proposed to Kate Middleton with arguably the most iconic ring in the royal family - his mother's 12-carat sapphire engagement ring.
However, a jewellery expert has warned that owning the precious heirloom doesn't come without its "challenges."
In her special "letter of wishes", included in her will, Princess Diana wrote: "I would like to allocate all my jewellery to the share to be held by my sons, so that their wives may, in due course, have it or use it.
"I leave the exact division of the jewellery to your discretion."
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The sapphire engagement ring is surrounded by 14 solitaire diamonds, set in 18-carat white gold, and estimated to be worth £390,000.
But according to Ben Roberts, Managing Director of Clogau – the brand responsible for the Welsh gold that the royals have used to create their wedding rings since 1923 - the upkeep of the ring is extremely difficult.
He told magazine: "Even without any alterations, caring for an heirloom of such value comes with its own challenges.
"Kate and her team will need to employ careful maintenance, with regular inspections and in-depth evaluations, gentle cleaning to restore sheen, and, if necessary, expert repairs to ensure its longevity.
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"That way, she can continue to wear it every day and maintain a constant connection to the past while grounding her in the present as a beloved senior member of the Royal Family."
At the engagement announcement, Prince William, who is understood to have popped the question during a trip to Kenya, discussed how he'd presented Kate with his late mother's ring.
He told ITV: "It's my mother's engagement ring and it's very special to me, as Kate is very special to me now as well.
"It was only right the two were put together.
He continued: "It was my way of making sure mother didn't miss out on today and the excitement and the fact that we're going to spend the rest of our lives together.
"I had been carrying [the ring] around in my rucksack for about three weeks before [the proposal].
"Everywhere I went, I was keeping ahold of it, cause I knew if this thing disappeared, I'd be in a lot of trouble."
'HONOURED'
It was previously reported that Kate had the sapphire ring adjusted as it was a little too big.
Jeweller G. Collins and Sons allegedly resized the ring by adding small platinum beads inside the band to reduce its diameter.
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However, the mum-of-three reportedly denied this during an event in Wales in 2023 and told fans: "It's the same ring and it was exactly the same size when I tried it on.
"I'm honoured to wear it, I never sadly got to meet her."