Queen Camilla looked elegant on Tuesday as she debuted a rarely-seen tiara at a glittering diplomatic reception at Buckingham Palace.

The Queen joined King Charles and the Prince of Wales for the grand white-tie affair yesterday evening.

Camilla, who has been recovering from a chest infection, looked stunning in a blue velvet evening dress by Fiona Clare and opted for the late monarch’s small aquamarine and diamond tiara as she gathered with some 900 guests at the Diplomatic Corps reception. The event is usually held in the run-up to Christmas rather than in November, but the King is hosting a state visit by the Emir of Qatar in the first week of December.

The delicate headwear – sometimes known as the aquamarine ribbon tiara – features five large aquamarines set in intricate ribbons of diamonds.

It was the first time Camilla has worn this beautiful piece of jewellery. Its history is not entirely clear.

Elizabeth had another larger aquamarine piece – the Brazilian Aquamarine Parure Tiara – which was made to match a necklace given to her by the president of Brazil as a coronation gift in 1953.

It is believed by some that the smaller tiara, worn by Camilla on Tuesday, was made from additional aquamarine jewellery gifted to the late Queen by the Governor of Sao Paulo.

The piece has been favoured in the past by the Duchess of Edinburgh, who previously wore it to the gala dinner celebrating the Hereditary Grand Duke Guillaume of Luxembourg’s wedding in 2012 and at the wedding of Princess Madeleine of Sweden in 2013.

Camilla teamed the tiara with an aquamarine and diamond necklace and earrings, which are private pieces of jewellery.

She also wore the King’s Family Order – a diamond-encased miniature portrait of her husband topped with a tiny gold and enamel Tudor crown and suspended on a pale blue silk bow on her left shoulder – which she first wore at the Japanese state banquet in June.

Family Order badges are worn at formal evening occasions by female members of the Royal Family and personally bestowed by the sovereign.

Royal fans loved Camilla’s look and took to social media to express their views.

One user wrote on Instagram: “One of my favourite tiaras and an unexpected choice for Camilla.”

Another one added: “Impressive dress and the tiara is great on her!”

Meanwhile a third one said on X: “She looks lovely. A perfect combination of colour style and the Tiara is divine.”

It is the first time the Queen has been pictured since Buckingham Palace announced on Monday that her beloved rescue dog Beth had been put down.