According to the source, the 102.56-carat diamond is a "vivid yellow colour".
Sotheby's claims the diamond piece is the largest of its kind ever sold at auction and has a guide price of between $7.4 million and $9.5 million, the website adds.
Around $60 million of jewellery will be on sale at the auction, which takes place on October 7th, the source concludes.
Meanwhile, jewellery auctioneers Venus Jewel has implemented a new section of its website which lists diamonds between 1.78-carats and 7.008-carats, reports Diamond World.
The section, which gives minimum prices for each diamond, is updated every Wednesday and has been running since the middle of September.