The 102.34 carat Type IIA diamond, the one, which is getting ready to be auctioned at Sotheby’s, is official the world’s largest, rarest and the most valuable round diamond in the world. Classified as D-Flawless category, the diamond does not have a name. It is the only diamond in existence, cut in round shape, while possessing all the four criteria of carats, color, clarity and cut.