Clarity: Clarity assesses the internal characteristics of the diamond as it formed in nature. This C factor is graded on a 10-grade scale and also impacts the diamond's rarity and value.
The fastest marathon ever was run by Geoffrey Mutai (2:03:02) at the Boston Marathon on April 18, 2011. But because the legendary Boston course does not meet IAAF layout standards, the World Record belongs to Patrick Makau (2:03:38) recorded at the Berlin Marathon on September 25, 2011.
This fall Dennis Kimetto set a new world record in the marathon, clocking 2:02:57 at Berlin. He is the first man to run those 26.2 miles in under 2:03 and his time sparked speculation about when the two-hour barrier for the marathon might fall.