One of the world's rarest diamonds is set to end up with a new and very rich owner later today. The diamond weighs 5.30 carats and is set in a Trombino ring made by renowned Italian jeweller Bulgari.
It is officially known as a 'fancy' diamond because of its intense colour. Deep-blue is one of the rarest colours the world. The ring was made in the 1960s and could fetch as much as £1.5 million at Bonhams Fine Jewellery sale.
There have only been 30 diamonds of this size and colour that have come up for sale over the last 10 years.