The story behind Diana’s iconic stone

UnDoUBTEDly the sapphire Diana wore most — second only to her engagement ring — was the eye-catching seven-strand choker with a gleaming, diamond-surrounded blue stone in its centre.

Dubbed ‘the necklace that stunned the world’ on its debut in 1985, at her brother lord Althorp’s 21st birthday at Spencer House in london, the central sapphire actually started life as a brooch, given to the Princess by the Queen Mother to mark her engagement.

The huge oval stone originated in Sri lanka, which accounts for a quarter of global sapphire sales, and may even have been mined from the same location as the stone in Diana’s engagement ring. The intense blue colour and high lustre of the stones makes Sri lankan sapphires very distinctive — and the most sought-after in the world.

Brooches were Diana’s least favourite style of jewellery. She thought them old-fashioned and ageing, so she wore the piece only twice, most memorably to adorn her formal regalia at a royal banquet at Hampton Court hosted by Queen Beatrix of the netherlands in 1982.

Early the following year, Diana had it refashioned — most likely with the help of the Spencer family jeweller Collingwood — into a choker. The oval stone set amid seven strands of shimmering pearls became one of her most iconic pieces of jewellery, which she continued to wear even after her divorce, often paired with sapphire or pearl drop earrings.

It was no coincidence that this was the piece she chose to wear with the infamous ‘revenge dress’, the form-fitting black gown by Christina Stambolian, which she debuted at the Serpentine Gallery’s summer party in June 1994, the same night as Prince Charles admitted his infidelity on TV.