Diana, however, chose her own engagement ring from the Garrad catalogue.

The ring in question, now belonging to Kate Middleton, is a 12-carat blue Ceylon sapphire surrounded by 14 solitaire diamonds with an 18K white-gold band.

James Harris, Diamond Jewellery Consultant at Diamonds Factory, estimates Diana’s ring to be worth between £300,000 – £700,000.

Royal fans can get the look with a gorgeous prong-setting blue sapphire halo ring, on a more modest budget, from Diamonds Factory.