Kate Middleton has to ask the Queen’s permission in order to wear one item

Being a royal entitles you to certain privileges – a designer wardrobe, personal chefs and if you’re the Queen, staff members employed to break in your shoes.

But it doesn’t come without its downsides, subjecting members to a life of obligation and rules, with an extremely large royal rulebook to follow.

From when Prince George, Princess Charlotte and Prince Louis should start bowing to the Queen to a ban on talking politics and no shellfish while on royal tours, there are too many to keep track of.

It's hardly surprising therefore that Meghan Markle reportedly had to undergo 'princess lessons' to learn everything from how royals hold tea cups to understanding the table settings - throwback to that famous Pretty Woman scene.

The strict rules on how royal women can descend staircases tends to make the most news, but this week it was a different protocol that caught the world's attention.

The rule in question that went viral this week surrounded Kate Middleton and her freedom to wear one particular necklace.

The Duchess of Cambridge has been spotted on several occasions wearing the Nizam of Hyderabad, and in order to wear it she needs Her Majesty's blessing.

This is not down to old traditions however, but more due to safety, with the Nizam of Hyderabad worth more than the Crown Jewels.

Yes, worth a whopping £66 million, the necklace has been described as a 'pavé-set centre with detachable double-drop pendant incorporating 13 emerald-cut diamonds and a pear-shaped drop; the chain of 38 brilliant-cut open-back collets with an elongated oval brilliant-set snap.'

It is the most expensive piece of jewellery in the world.

It is for this reason that it is rarely worn by royals, and on the odd occasion when Kate Middleton does wear it, the Queen's permission has to be granted.

Well, that's that.