Describing the ring, they said: “Kate Middleton’s ring, which was formerly Princess Diana’s, features a 12ct Ceylon sapphire, originating from Sri Lanka.

“Like with most precious gemstones, the quality and value of a sapphire is graded by its colour and hue, which can range from a light, pale blue to a dark, royal blue.

“The sapphire is a deep, royal blue, of AAAA quality, making it amongst the most valuable of its kind.”

The central jewel was surrounded by a cluster of 14 solitaire diamonds set in 18ct white gold.

The marvellous ring had extreme cultural significance at the time, with the sale of blue sapphires increasing by 300 percent globally.