Royal Wedding: Kate Middleton's Tiara

PHOTO Kate MiddletonPlayCourtesy of Women?s Wear Daily
WATCH Royal Diary: Kate's Top Tiaras

There has been plenty of chitter chatter about Kate Middleton's wedding dress but less about the cherry on top: the tiara.

All princesses -- Disney ones included -- have glittery headwear. And the centerpiece accessory is of utmost importance for a princess on her wedding day.

Traditionally, Queen Elizabeth II has given a royal bride a tiara as a wedding gift. After all, she has the pick of the largest selection of tiaras in the world from what's famously dubbed the "jewel pool."

The queen could choose the "Fringe" tiara, which she wore on her wedding day to Prince Phillip, the Duke of Edinburgh.

Or maybe the grand "Girls of Great Britain and Ireland" tiara given to the queen by her grandmother, Queen Mary?

Then there's the "Durbar" tiara, which the queen loaned to daughter-in-law Camilla Parker Bowles for a state banquet.

"All these tiaras are so valuable in their provenance," Simon Perry of People magazine said about the selection of tiaras worn by Diana, Queen Elizabeth and the queen mother.

"I would think they are priceless. To put them on sale now would be impossible."

On her wedding day in 1981, Princess Diana dove into her own family vault and wore the Spencer family tiara.

Middleton already has Diana's engagement ring, so perhaps she would consider wearing her tiara.

William's aunt, Sarah Ferguson, who is not invited to the April 29 wedding, famously wore a garland of flowers into Westminster Abbey on her wedding day. Her headwear symbolized a commoner's entering the ceremony.

After the vows, the flowers came off to reveal a new tiara commissioned by Garrard Jewelers, highlighting a new Ferguson, Duchess of York.

Heirloom Might Be in Store for Middleton

Some experts suggest that the queen will give Middleton an heirloom tiara to wear on her big day.

"Given the multitude of Garrard tiaras that are in the royal family possession, it is likely there will be one that has carried on down the generations that she would wear," Eric Deardorff, CEO of official royal jewelers Garrard, told ABC News.

Garrard is the world's oldest jeweler. It produced Diana's ring and some of the queen's tiaras.