Kate Middleton
Photo: Getty

Kate Middleton has previously been seen wearing tiaras and brooches, but today she stepped out “new” royal jewels. For a state dinner at Buckingham Palace tonight, the Duchess of Cambridge donned a diamond and pearl necklace that’s over a century old and has been running in the royal family for generations.

Here’s what you need to know about the stunning piece of jewelry, which the Kate wore with a sleeveless blue Alexander McQueen gown and Lover’s Knot tiara.

Kate Middleton
Photo: Getty

It originally belonged to Queen Alexandra.

According to royal blog Order of Splendour, the necklace was a gift from Queen Victoria’s son, the Prince of Wales (who would later become King Edward VII) to his wife, Princess Alexandra of Denmark (later known as Queen Alexandra), to celebrate their wedding in 1863. The necklace was part of a whole set, which included the “Rundell” tiara (which has since disappeared), a brooch, and earrings.

Related article: Kate Middleton is Wearing The Lover’s Knot Tiara At The State Banquet

Queen Alexandra, King Edward VII
Queen Alexandra (wearing various necklaces) and King Edward VII on his coronation day.
Photo: Getty/ Hulton Archive

It features eight pearls surrounded by diamonds.

The stunning piece features “eight large pearls surrounded by diamonds and connected by diamond festoons with drop pearls hanging from the central clusters,” according to Order of Splendour.

Queen Alexandra’s jewels
A sketch of Queen Alexandra’s jewels from her husband.
Photo: Getty/Print Collector

Related article: The Story Behind Prince Harry’s Surprising New Ring

The Queen Mother loved it.

The Queen Mother, Queen Elizabeth II‘s mom, was a big fan of the piece of jewelry. In fact, she reportedly wore it during a previously state banquet honoring the Netherlands back in 1982. It appears Kate is simply following tradition, as tonight’s state banquet honors Dutch royals, King Willem-Alexander and Queen Maxima.

She also appeared to wear the necklace while celebrating her 85th birthday in 1985, and during a formal appearance in 1964.

Queen Mother
The Queen Mother wearing the necklace in 1985 and 1964.
Photo: Getty

The necklace has been passed down through generations, from Queen Alexandra to her son King George V’s wife, Queen Mary; then to her son King George VI’s wife, Elizabeth Bowes-Lyon (AKA the Queen Mother); and then to her daughter, Queen Elizabeth II. The current sovereign reportedly inherited the piece in 2002, according to Her Majesty’s Jewel Vault, but she hasn’t been seen wearing it in public.

Kate is certainly wearing a lot of history with her outfit tonight.

Related article: The Sweetest Photos of The Royal Family Kissing Through The Years

This post originally appeared on Harper’s Bazaar US.