Sapphires hold a deep personal significance for the Queen.

Her priceless collection of jewellery contains a suite of deep blue gemstones given to her on her wedding day by her father.

George VI's gift to his eldest daughter Princess Elizabeth in 1947 - 70 years ago - was a glittering necklace, dating from 1850 and made of 16 large oblong sapphires surrounded with round diamonds, with a pair of matching sapphire and diamond drop earrings.

The Queen added a sapphire and diamond tiara - made from a necklace that originally belonged to Princess Louise of Belgium - and a bracelet in 1963 to the collection to compliment the original sentimental pieces.

Noel Coward once wrote, after being introduced to the Queen while she was wearing the King George VI Victorian Suite, that they were 'the largest sapphires I have ever seen', according to Leslie Field, author of The Queen's Jewels.

The monarch has worn them many times including to a state banquet in Prague in 1996, and - minus the tiara - to a family party to mark her Golden Jubilee in 2002 and her 80th birthday party at The Ritz in 2006.

George VI also gave her sapphires for her 18th birthday - a distinctive, slim Cartier linked bracelet of square cut sapphires and diamond baguettes.

When Prince Charles was born in 1948, Princess Elizabeth's parents also presented her with a brooch of ruby, diamond and sapphire flowers to mark the happy family occasion.

The royal love of sapphires dates back to a romantic Prince Albert. The day before his wedding in 1840, he gave Queen Victoria a brooch made of a large oval sapphire encased in 12 round diamonds.

It has been handed down through the generations to Elizabeth II after Victoria, who loved the brooch, left instructions in her will for it to become a piece of Crown jewellery and held in trust for all future queens.

Sapphires are said to be the symbol of love and purity, and many royal brides-to-be have chosen a sapphire engagement ring.

Famously Diana, Princess of Wales's ring was a 12-carat oval sapphire set in a cluster of 14 brilliant-cut diamonds.

It is now owned and worn by the Duchess of Cambridge, after Prince William gave it to her on their engagement in 2010.