A flawless, un-included (perfect) diamond of 100 carats or more. In the 16th century perfect diamonds of 12 carats or more qualified as a paragon, but the definition has evolved. A 100 carat diamond weighs 20g. The largest flawless diamond in the world is known as ‘The Paragon’ and weighs a whopping 137.82 carats, or 27.56g.