Kate Middleton recently wore a stunning 38-diamond necklace that reportedly has a fascinating story.

Unlike some of the jewelry that the Duchess of Cambridge has worn, the necklace that she chose to wear at the state banquet doesn’t belong to the Royal Collection. Rather, it is personally owned by Queen Elizabeth II and is made of platinum and diamonds.

The necklace is actually called Nizam of Hyderabad, and it is distinctly different from other necklaces because of its length, shape, and weight. According to Emily Hodgkin, a journalist for Express, the necklace could give royal fans an insight into the taste of Her Majesty, which is oftentimes ruled by her duty and not her personal preference.

Several years ago, the monarch picked out the necklace herself from Cartier’s collection after Nizam of Hyderabad, Asaf Jah VII, instructed the French jewelry house to allow the then-princess to choose anything that she wants.

The Queen chose the necklace that Middleton recently wore, and it also features 12 emerald cut-diamonds and a pear-shaped drop plus a chain of 38 brilliant-cut diamonds. The necklace also came with a matching tiara, which is also made from platinum and diamonds and has a huge central stone made out of diamonds.

Hodgkin said that even though the Queen personally chose the necklace years ago, it seems that she might have fallen out of love for it. Her Majesty broke the necklace and used some of its parts to create the Burmese Ruby Tiara. But she kept the floral brooches from the tiara.

Middleton’s recent sighting with the jewelry was actually not the first time that she has worn it. Prince William’s wife also wore the necklace on Feb. 11, 2014, at the National Portrait Gallery.

Meanwhile, Her Majesty wore the Burmese Ruby Tiara at this week’s state dinner with the president of the United States and the other members of the royal family.