From today, you can see this gorgeous 110-carat pear-shaped yellow diamond in The Vault gallery thanks to the generosity of Cora diamond manufacturers who have loaned us the gem.
Model Jerry Hall is dazzled by the arrival of the Cora Sun-Drop in The Vault gallery (Image copyright Adrian Brooks - Imagewise)
These large (over 100 carat) coloured diamonds are extremely rare in nature and are historically significant as so few exist. So it's a privilege to be able to have the Cora Sun-Drop on show to our visitors.
'When you look at a diamond like this you are not only looking at a unique piece of art, you are looking at the fascinating science that bought this stone to us.
'The Cora Sun-Drop diamond was formed deep within the Earth’s crust 1-3 billion years ago. As it grew, it incorporated nitrogen into its carbon crystal structure. It is these nitrogen impurities that give the diamond its yellow colour as they modify light, absorbing the blue part of the visible spectrum. The diamond then travelled on a long journey upwards in a slushy rock magma. After it was found within a kimberlite pipe (a type of volcanic rock), it was expertly studied and cut, bringing the diamond to life.
'Good quality coloured diamonds, known as "fancy" diamonds, are extremely rare. Only about 1 in 10,000 mined diamonds are thought to have good body colour, and only a small percentage of these are considered to have good enough clarity to be labelled as a fancy diamond.
'The Cora Sun-Drop combines both a vivid yellow colour and another rare quality, a large size. At just over 110 carats, it is not only exceptionally large, it is the largest yellow pear-shaped diamond known.'
But diamonds aren't forever, I'm afraid! The Cora Sun-Drop is only with us in The Vault for a limited time, so bask in its light while you can. And don't forget there are 300 other diamonds in The Vault, including the Aurora collection, as well as a model of the famous Koh-i-Noor diamond.
You can hear Alan Hart talk about our impressive diamonds and gemstones at The Treasure Trove talk here in the Attenborough Studio on 25 March at 14.30.
And in case you wondered what the largest faceted diamond in the world is? At a whopping 545.67 carats, it's said to be the Golden Jubilee, also known as the Great Star of Africa, which now resides in the Royal Thai Palace as part of the crown jewels.
Pear-shaped Cora Sun-Drop image right courtesy Tom Tragale for M Patricof, Creative Group