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.
In 1983 Mike Boit of Kenya ran a mile in 3:28.36. As far as I know, no one has ever covered the distance faster. This was on a downhill road course so it isn't recognized by IAAF but it's still the fastest mile ever run by a human. The world record in the mile run is the best mark set by a male or female runner in the middle-distance track and field event.