Heartwarming detail in Queen and Prince Philip's wedding anniversary portraits

Queen Elizabeth II and Prince Philip, Duke of Edinburgh in their 73rd anniversary portrait. Photo / Chris Jackson / Buckingham Palace / Instagram

The Queen and Prince Philip have officially been married for 73 years. And it appears the Queen's jewellery is as long-lasting as her marriage.

The couple posed in adorable portraits with a familiar detail.

In the photos taken at Windsor Castle, the Queen and the Duke of Edinburgh can be seen looking at a homemade card given to them by their great-grandchildren, Prince George, Princess Charlotte and Prince Louis.

Looking regal in a powder-blue dress and pearls, the Queen can also be seen wearing one of the oldest pieces from her jewellery vault – the sapphire chrysanthemum brooch.

The brooch was gifted to her in 1946 when she launched the British Princess oil tanker in Sunderland.

She was also seen wearing it in official honeymoon photos taken five days after her November 1947 nuptials with Prince Philip.

The pair posed in beautiful black and white portraits at Broadlands Estate, Hampshire, when the royal was still known as Princess Elizabeth.

The royal couple on their honeymoon in 1947. Photo / AFP

They recreated the honeymoon photos at Broadlands for their 60th anniversary in 2007, when the Queen wore the brooch again.

The brooch features diamond petals and a sapphire centre to form a chrysanthemum design.

The Queen has a fabulously extensive jewellery collection. The Crown Jewels, which she inherited when she was crowned in 1953, are said to be worth about NZ$6.7 billion.

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Tiaras from the Queen's personal collection have been loaned down the line over the years. Catherine, Duchess of Cambridge wore a Cartier Halo tiara for her 2011 wedding to Prince William, valued at NZ$2.3 million.

Meghan, Duchess of Sussex wore a bandeau diamond tiara worth NZ$3.8 million for her 2018 wedding to Prince Harry.

Princess Eugenie borrowed the Queen's Greville Emerald Kokoshnik Boucheron tiara for her wedding, which is reportedly worth more than $20 million. Photo / AP

But Princess Eugenie's wedding tiara was the most expensive by a long shot. The Queen's granddaughter wore a Greville Emerald Kokoshnik Boucheron tiara, created in 1919, for her 2018 wedding to Jack Brooksbank.

It is reportedly worth up to $23 million.