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.
That is because, according to the Age-Graded Scoring tables, the ideal finish time for a 55-year old male is 2:24:22, and that's about 20% faster (about 36 minutes) than our 55-year old ran. Now let's say that a 27-year old male ran the same marathon in 2:45:47. Obviously, that is faster than our 55-year old.