Diana donned the choker on her head at a state banquet held by the Emperor of Japan in his native country in 1986.

The late Princess matched the headpiece with a pair of sapphire and diamond earrings and a flowing silk gown, also in royal blue.

Apart from the fact it was worn by Diana has a headpiece, what made the choker unique was it was first two separate jewellery pieces: a ring and a watch.

These were given to Diana by the Crown Prince of Saudi Arabia, before the Princess had them transformed into a velvet choker.