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.
I'm running a marathon and I'm not sure what pace to run. How can I estimate my marathon finishing time?. Finishing times for marathons (26.2 miles) range from a little over two hours for world-class, elite marathoners to 8+ hours for walkers.