Sophie, Countess of Wessex: She is the wife of Prince Edward (Image: EXPRESS)
"The most sought after aquamarines have an intense ocean-blue colour and are completely clear of internal marks or inclusions."
Sophie has worn her ring on various occasions and, like the ring previously owned by Princess Diana, it could be worth a small fortune.
Tobias stated: "Countess Sophie's ring is about 20-carat, and should be worth around £16,000.
"Her ring seems to be set with two side gemstones, in a trilogy design."
It is one of many eye-catching rings the royal has worn while in the family.
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