The tiara, a platinum scroll with a floral pattern, was purchased for Ms Ferguson as a wedding gift by the Queen and the Duke of Edinburgh for her marriage to Prince Andrew in 1986.
Diamond collets are fixed onto the tiara and a large diamond of around five carats sits on its top.
After the Duchess of York married Prince Andrew, some commentators suggested the tiara had been her ‘something borrowed’ and was lent by a friend.
But it later was revealed it that unlike Princess Diana, who wore her family tiara for her wedding, Ms Ferguson did not have a family tiara, and so the Queen and Prince Philip purchased her one from the jewellers Garrad as a wedding present.
The tiara was given as part of a demi-parure, a set of jewellery with typically three pieces, which also included a necklace, earrings, and a bracelet.
It has been over a decade since it was last seen at the White Tie and Tiara Ball hosted by Sir Elton John at his Windsor mansion on 5 July, 2001.
Ms Ferguson kept the tiara following her split from the Duke of York in 1992.
Earlier this year, a gemologist told Express.co.uk: “This picture-perfect classic is made entirely out of diamonds set in platinum with floral scrollwork and a large diamond of around 5 carats sitting on top.
“The value of such a piece is not easy to calculate without knowing details about the diamond sizes, qualities, and also the weight of the platinum.
“That being said, with the value of a top quality 5 carat stone like this tiara topper combined with the platinum and other diamonds, the value of this tiara would easily be more than $300,000 USD today.”
But this is far from Princess Eugenie’s only option, as Queen Elizabeth often loans royal brides pieces from her personal collection.
Other options for Princess Eugenie include:
Strathmore Rose Tiara
For an understated look, Princess Eugenie could choose this Strathmore Rose Tiara. It was given to the Queen Mother as a present by her parents 1923.
This is best worn on top of the head but can be worn across the forehead as a beandeau. The elegant floral piece has not been seen in public for years.
The Queen Mother wore the tiara after her wedding ceremony at Westminster Abbey, London in 1923.
Queen Alexandra’s Russian Kokoshnik Tiara
One of the largest tiaras, Eugenie could choose this if she wanted to make a big impression with this striking fringe headdress.
It is composed of an astonishing 61 platinum bars and dazzling 488 diamonds.
This was gifted to Alexandra on her silver wedding anniversary in 1888 and is based on the Russian-style of peasant girl’s headwear, very stylish at the time.
Queen Mary’s Girls of Great Britain and Ireland Tiara
It would be surprising if Eugenie wore this tiara, which is associated with the monarch.
It is one of the Queen’s favourites, and she often wears it.
But it is still possible Queen Elizabeth would lend it to Eugenie for her special day.