This is why Meghan Markle can't wear Kate Middleton's wedding tiara

Guess she'll have to choose from a hundred others then.

While everybody’s speculating about who’s going to be Meghan Markle’s wedding dress designer, we now know one thing for sure - she won’t be wearing an iconic piece of royal jewellery on her wedding day. More specifically, Kate Middleton’s wedding tiara isn’t going to be making an appearance as it’s off on tour.

Kate’s Cartier ‘Halo’ tiara is currently making the rounds in Australia, where it’s one of the centrepieces of a fine jewellery retrospective called Cartier: The Exhibition. However, the exhibition runs from March 30 - July 22 and Meghan’s wedding to Prince Harry is smack bang in the middle of it on May 19, meaning it won't be available.

The tiara is an important part of royal history beyond Prince Harry and Kate's wedding, as it was Queen Elizabeth II’s 18th birthday gift from her own mother, who was given it by her husband King George VI. (It's the ultimate hand me down.) The platinum tiara features almost 900 diamonds, set with a crowning centrepiece diamond in the middle.

Although Meghan won’t be picking up Queen Elizabeth’s Halo for her big day, we’re sure she’s spoiled for choice - she is marrying into the family that owns the royal jewels, after all. When her sister-in-law-to-be isn’t donning one of her iconic Kate Middleton hats, Kate's previously borrowed accessories such as a pearl-embellished Princess Diana tiara and Queen Elizabeth’s Lotus Flower Tiara. It wouldn't be unheard of for the royal family to loan Meghan something sparkly for her big day.

Given that Meghan Markle will apparently be taking style pointers from the late Princess Diana’s style playbook, we have a strong feeling that she’ll probably wear one of her mother-in-law's accessories. We for one think it’s about time the Spencer came out of the woodwork, as it’s too beautiful a piece to be collecting dust in a drawer somewhere. Plus, it would be a sentimental gesture given that it was Princess Diana's wedding tiara as well.

Kate’s wedding tiara will be joined by over 300 other pieces of Cartier bling, which have belonged to a whole range of people including celebrities, billionaires and more.

It’ll be in royal company alongside Princess Grace of Monaco’s 10.48 carat diamond engagement ring, as well as Dame Elizabeth Taylor’s show-stopping diamond and ruby necklace.