The stunning piece of jewellery features a 12-carat oval Ceylon sapphire surrounded by 14 solitaire diamonds in a marguerite design, and set in 18-karat white gold.
The Duchess of Cambridge was apparently not meant to receive the ring at all, as upon Princess Diana's passing, and when her sons turned 18, the ring was passed onto Prince Harry for his future wife, while Prince William got his mother's Cartier ring.
However, when Harry realised William wanted to propose to Kate, he decided to give him the sapphire, knowing it would be perfect for her.
During their engagement announcement, Prince William said of the ring, 'Obviously, she’s not going to be around to share in any of the fun and excitement of it all, so this is my way of keeping her sort of close to it all.'
This romantic gesture did raise some eyebrows at the time though, with some critics saying it wasn't a good omen to propose with a ring that came from an unhappy marriage.
Prince Charles and Princess Diana married in 1981 and officially divorced in 1996, though they separated in 1992.
Luckily, The Duke and Duchess of Cambridge have proven those critics wrong.
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Penny Goldstone is the Digital Fashion Editor at Marie Claire, covering everything from catwalk trends to royal fashion and the latest high street and Instagram must-haves.
Penny grew up in France and studied languages and law at the Sorbonne Nouvelle University in Paris before moving to the UK for her MA in multimedia journalism at Bournemouth University. She moved to the UK permanently and has never looked back (though she does go back regularly to stock up on cheese and wine).
Although she's always loved fashion - she used to create scrapbooks of her favourite trends and looks, including Sienna Miller and Kate Moss' boho phase - her first job was at MoneySavingExpert.com, sourcing the best deals for everything from restaurants to designer sales.
However she quit after two years to follow her true passion, fashion journalism, and after many years of internships and freelance stints at magazines including Red, Cosmopolitan, Stylist and Good Housekeeping, landed her dream job as the Digital Fashion Editor at Marie Claire UK.
Her favourite part of the job is discovering new brands and meeting designers, and travelling the world to attend events and fashion shows. Seeing her first Chanel runway IRL at Paris Fashion Week was a true pinch-me moment.
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