She wore the Cartier Halo tiara for her wedding to Prince William, and has also worn the Lover’s Knot tiara.
According to a source Kate has come up with a “clever” way to get access to them.
A source told Grazia: “Kate gets the pick of the jewels for big occasions and the Queen is happy to open up her jewellery box.
“Kate has been clever to befriend Angela Kelly, who is in charge of the Queen’s personal jewellery collection and oversees the loans.
“Generally, Kate is allowed to borrow whatever she fancies.”
Meghan Markle is yet to wear any of the Queen’s jewellery, something royal fans have not failed to notice.
It was claimed the Queen assured William Meghan would not wear any jewellery worn by Diana from the royal collection.
Journalist Dan Wootton discussed the story on ITV’s Lorraine back in April.
He explained: “The Queen is in charge of the royal collection, a massive collection of all of the artefacts that the country and the Royal Family own.
“Included in that are some iconic prices of jewellery, many of which have been leant to Princess Diana.
“We’ve seen Kate wear certain items from the royal collection.
“The Queen has to give permission for any member of the Royal Family to wear any of these items of jewellery.
“The Queen has actually banned Meghan from wearing any pieces of this jewellery and the Queen personally assured Prince William this includes any piece that was worn by Princess Diana.”
However, Meghan has worn Princess Diana jewellery from the late Princess of Wales’ private collection, which was left to her sons.
She wore Diana’s aquamarine diamond ring with a stunning Stella McCartney dress for her wedding reception with Prince Harry.
A look at the wedding tiaras worn by recent royal brides
Sophie, Countess of Wessex wedding tiara
While royal brides tend to either wear a brand new piece or a wear an heirloom piece, Sophie, Countess of Wessex wore a combination of the two.
The exact name of the tiara is unknown.
The Countess has worn the piece of jewellery a number of times since her wedding day – such as to the nuptials of Crown Prince Frederik of Denmark and Crown Princess Mary of Denmark.
Sarah Ferguson wedding tiara
Sarah Ferguson tied the knot with Prince Andrew at Westminster Abbey in July 1986.
Sarah Ferguson also wore a previously unseen wedding tiara, with the jewellery having been made especially for her.
Princess Diana wedding tiara
Princess Diana was known as Lady Diana Spencer before marrying Prince Charles back in 1981.
The royals tied the knot at St Paul’s Cathedral.
The late princess opted for her own family diamonds for the occasion, wearing the Spencer Tiara.
Meghan Markle wedding tiara
Meghan Markle, the Duchess of Sussex, wore the Queen Mary Bandeau Tiara for her and Prince Harry’s big day.
The former Suits actor tied the knot with the prince in May 2018, at St George’s Chapel, Windsor Castle.
The jewels hadn’t been worn for 65 years prior to the special event, having previously been well-loved and worn by Queen Mary, the grandmother of Queen Elizabeth II.
Kate Middleton wedding tiara
Kate Middleton and Prince William wed at Westminster Abbey, London, back in 2011.
The Duchess of Cambridge arrived at the church in the Cartier Halo Tiara.
It is set with more than 1000 diamonds, and crafted as a band of “16 graduated scrolls”, the Royal Collection Trust have said.