Cora Sun-Drop Diamond
The Cora Sun-Drop Diamond is the largest known yellow pear-shaped diamond, weighing . It was sold for $10.9 million at Sotheby's auction in Geneva and set a world record price for a yellow diamond.

History 
The Sun-Drop has a very short history. It was found in South Africa in 2010 within a kimberlite pipe. Tests show that the diamond was formed from 1 to 3 billion years ago. After that, on 24 February 2011, it was kept in The Vault of the London Natural History Museum together with many other precious stones, such as the Duke of Devonshire Emerald and the Aurora Pyramid of Hope, where it stayed for six months. In November 2011, it was sold at an auction in Geneva for just over $10.9 million. 
The stone was cut and owned by the diamond manufacturing company Cora International, based in New York City. It was sold at the auction by Sotheby's. The Sun-Drop was bought by a telephone bidder who decided to remain anonymous. Including commission and taxes the buyer paid $12.36 million. The pre-sale estimate was from 11 to 15 million dollars. "It sold for a record for a yellow diamond ... It was exactly within our expectation for this spectacular stone," said Mr Bennett, an auctioneer.

Colour 
The intense yellow colour, or "vivid fancy yellow" as the experts called it, is given  to the diamond by molecules of nitrogen that have been trapped in the molecules of carbon and hardened over thousands of years. Yellow is the fifth most rare colour for a diamond, after red, green, blue and pink. Good quality diamonds are termed "fancies" by dealers. Only 1 in 1000 diamonds is good enough body colour to be called fancy.

Cut 
The diamond was cut as a pear brilliant, also called drop cut. Suzette Gomes, the chief executive at Cora international said that the cut is vital in bringing out the diamond's beauty. She said: "If the colour is weaker you would cut a square... to keep the colour and make it stronger. If your colour's very strong, you would cut a pear shape." Cutting the Sun-Drop took Cora International six months.

See also
 List of diamonds

References

 https://www.bbc.co.uk/news/world-europe-15746900
 https://www.bbc.co.uk/news/world-europe-15732260
 https://www.bbc.co.uk/news/science-environment-12556341
 https://www.theguardian.com/science/video/2011/feb/24/cora-sun-drop-diamond-museum
 http://www.nhm.ac.uk/natureplus/blogs/whats-new/2011/02/22/our-new-cora-sun-drop-diamond-sets-the-vault-gallery-ablaze?fromGateway=true
 http://www.nhm.ac.uk/about-us/news/2011/february/worlds-largest-yellow-pear-shape-diamond-dazzles-in-museum94850.html
 http://www.nhm.ac.uk/visit-us/galleries/green-zone/vault/index.html
 http://www.sothebys.com/en/auctions/2011/magnificent-jewels-ge1105/overview.html
 http://www.luxist.com/tag/cora+sun-drop+diamond/ 
 https://archive.today/20130126033459/http://hungeree.com/culture/cora-sun-drop-diamond/
 http://www.digitalhen.co.uk/news/world-europe-15749526
 http://www.diamondpriceguide.com/news/88934/show
 "Gemstones" by Keith Wallis FGA

Diamonds originating in South Africa
2010 in South Africa
Individual diamonds
Yellow diamonds