Which royal tiara could Meghan Markle wear on her wedding day?

With the big day just weeks away, many are speculating which tiara she'll wear.

Royal brides have typically worn a headpiece from the extensive royal vault of jewels.

Here are some of the popular tiaras donned by royals in the past:

Spencer tiara

While many royal watchers deem it unlikely, Harry may ask if his bride can borrow the tiara for sentimental reasons.

Harry, 33, and Markle, 36, have included a nod to Harry's late mother as they plan the wedding, with Markle's ring including two diamond stones from Diana’s jewelry collection.

Lotus Flower tiara

It is a distinct possibility Markle could wear this tiara, passed down through the Windsor women.

Princess Diana’s emerald choker

The emerald and diamond choker, which Harry's late mother also wore as a headband, is one of the most iconic pieces associated with the late Princess of Wales. Designed by Garrard in the 1920’s for Queen Mary, the necklace was a wedding gift to Diana from Queen Elizabeth.

Kate has never worn the piece and royal brides have been known to refashion pieces from the extensive jewelry collection that exists.

Markle and Harry could adapt the necklace associated so closely with Diana to create an unforgettable, one-of-a-kind sentimental piece that Markle could wear even after her wedding day.

Diana also had a sapphire and diamond choker that could be similarly created into a tiara for Markle's wedding day.

Cambridge Lovers Knot tiara

Diana’s favorite tiara was created by the Queen Elizabeth’s grandmother, Queen Mary, in 1913. It was a gift to Diana on her wedding from the monarch.

When Diana died in 1997, it was returned to Queen Elizabeth.

Diana said the tiara was made of 19 diamond arches and stunning hanging pearl drops. Kate has now borrowed and worn the tiara several times as the Duchess of Cambridge, reflecting the tiara’s historical provenance and name.

It may not be the first choice as a wedding tiara for Markle since Kate has started wearing it to various state functions.

Cartier Halo Scroll tiara

The tiara, which once belonged to the Queen Mother, would be an elegant yet understated piece for Markle.

Diana’s jewels

While many brides dream of being a princess for a day, Markle's humble beginnings will see the California native celebrating her own fairy-tale ending.

She will have access to some of the spectacular jewels in Diana’s personal jewelry collection, which were not returned back to Queen Elizabeth and left to her two sons, William and Harry.

After Diana's death, in a "Letter of Wishes" which became part of her will, Diana explained that she was passing her priceless jewelry to her sons so their future wives would one day have to use.

"I would like you to allocate all my jewelry to the share to be held by my sons, so that their wives may, in due course, have it or use it," the letter reads. "I leave the exact division of the jewelry to your discretion."

One of the most jaw-dropping pieces in Princess Diana’s jewelry box was the sapphire and seven-strand pearl choker she wore before and after her divorce from Prince Charles.

Princess Kate has never worn the iconic necklace. She has regularly worn other pieces in Diana’s extensive collection so it may have been one item William and Harry decided to save for Harry's future wife.

The sapphire was initially given to Diana, the Princess of Wales, by the Queen Mother as a wedding gift and she later refashioned it into the necklace.

Diana was also gifted an extensive collection of sapphires by the Saudi Crown prince on her wedding day, which she wore throughout her life.

William presented Kate with a pair of sapphire earrings matching Diana’s engagement ring, believed to be from Saudi sapphires.

There are several pieces that Kate has never worn from the collection that we may see Markle make her own in the years ahead.