title: Cullinan Diamond
context: The Cullinan Diamond is the largest gem-quality rough diamond ever found,[2] weighing 3,106.75 carats (621.35g), discovered at the Premier No. 2 mine in Cullinan, South Africa, on 26 January 1905. It was named after Thomas Cullinan, the mine's chairman.
question: What is the biggest diamond?
answers: Cullinan Diamond