Kate Middleton will receive the Royal Family Order of Queen Elizabeth II

The Duchess, 33, is set to be honored with the Royal Family Order of Queen Elizabeth II, a title that is the highest honor that the Queen can bestow upon a female royal family member.

According to sources cited by Vanity Fair, this title will be granted to Kate by next month. The order is in the form of an diamond-encrusted brooch with an ivory plaque depicting the Queen wearing the Order of the Garter.

Princess Diana, Sophie, Countess of Wessex, Princess Anne, Princess Royal, Camilla, Duchess of Cornwall, are among the royals who have previously received this Order.

The royal couple and their two adorable children, Princess Charlotte, 4 months, and Prince George, 2, were at Balmoral on Wednesday to celebrate the Queen’s milestone day.

Kensington Palace tweeted a message on the big day, along with some pictures of the monarch.

“Today we are marking an inspiring milestone in The Queen’s service to the UK and Commonwealth #longestreign ” the tweet read.

Her grandson, Prince William, praised her last month, saying, “I am privileged to have The Queen as a model for a life of service to the public.”