During her time in the family, Sophie has also worn two other tiaras and will usually dig them out for special occasions.
As well as show-stopping jewels, the royal will sometimes make more subtle jewellery choices.
Royal fans will have noticed Sophie wear a long chain with a small stone and initial pendants on it.
The necklace has the initials ‘E’, ‘L’ and ‘J’ on the chain.
These are the initials of her husband, Prince Edward, her daughter, Lady Louise Windsor, 16, and her son, James, Viscount Severn, 12.
James Constantinou, founder of Prestige Pawnbrokers and star of Channel 4’s Posh Pawn, said: “Sophie, The Countess of Wessex – married to Edward, Earl of Wessex – is a member of the Royal Family with a jewellery collection reportedly worth over £3million.
“The Countess has worn this necklace on many royal appointments.
“It has the charm of a vintage piece but not only that it has beautifully crafted initials added to hang next to the stone.
“‘E’ for her husband, ‘L’ for her daughter Lady Louise Windsor and a ‘J’ for her son, James Viscount Severn.
“This necklace on a chain has been worn many times before, once with a shell clam which she has since removed.”
The necklace has a special link to her family and she has been spotted wearing it at official engagements.
While it is unlikely Sophie would ever part with the necklace, it could be worth a huge amount of money.
Although the jewel is subtle, its family link would make it popular among many royal enthusiasts.
James told Express.co.uk: “As with other extraordinary pieces from the royal household, the quality is outstanding.
“Sometimes you just can’t always put a price on a personalised piece of jewellery, especially when details on the stone in terms of clarity and weight are not known.
“However, it would be fair to say that a piece such as this with its royal connection along with added historic value could be worth in excess of £250,000.”