This is not the only colourful piece of jewellery Kate likes to wear, however.
Diamond expert at Austen & Blake Anthony French explained Kate – and others in the Royal Family – are not afraid of a pop of colour.
He said: “The royals are not shy when it comes to wearing colour, but it isn’t for everyone and that’s ok.
“Adding colour subtly using your accessories is a great way to add interest to any outfit.”
By choosing colourful jewels, Kate could be trying to “add interest” to her looks, the expert explained.
Kate has done this by matching her jewellery to colourful outfits.
This is different to royals such as Meghan Markle, the expert claimed, who has previously worn colourful jewellery with neutral outfits.
Anthony added: “Meghan is a great example of this as she tends to opt for small pops of colour in her jewellery, often complementing a more neutral or colourless outfit.
Anthony added using colourful jewellery is something anyone can replicate at home.
He recommended doing this to brighten up an outfit and “add elegance”.
“When choosing your jewellery, try reaching for a ring or necklace with a coloured gemstone, such as a ruby or emerald,” the expert stated.
“Not only with this add a pop of colour, but a splash of elegance too.”
The royal line of succession – who outranks who?
The line of succession to the British throne dictates the order in which each member of the Royal Family would ascend to the throne.
It is also seen as a ranking of importance with the head of the line, the Queen, taking the place of ruler.
Older children come before younger children. Traditionally boys came before girls, but this law was changed on March 26, 2015 before the birth of Prince William’s first child.
Incredibly, Catholics are still excluded from the line of succession, as are children born outside of wedlock.
The royals, who usually stick to a strict protocol when appearing in public, often arrive at events in ascending order of importance, with the most important royal arriving last.
Prince Charles, 72, is currently first-in-line to the British throne, followed by Prince William, 39, his oldest son.
Then comes Prince William’s children, George, seven, Charlotte, six, and Louis, three, and they are followed by Prince Harry, 36. Prince Harry is succeeded by his son Archie Harrison, born in May 2019.