“It is studded with diamonds set in a white precious metal more likely to be platinum because of the era it was made. It is perceived to be made by Cartier in France.

“It is not known how much the tiara is worth, but Papas estimates it to be worth over £1million and if it is a Cartier piece, it could be as much as £2million to £4million.”

The royal first met her union rugby league player husband nearly 20 years ago, in 2003.

Their engagement was announced seven years later in a statement that came from Buckingham Palace.

Zara was given a beautiful diamond ring with a classic design which has a valuation of around £140,000.