Thats more than 10000 times the speed of the orbiting space shuttle. The definition of index of refraction is. HOPE THIS HELPS YOU.
The very top of the Wikipedia article on Snells law has your answer.
Diamond has a refractive index of 242 which means that the speed of light in diamond will reduce by a factor of 242 as compared to its speed in the air. Thats more than 10000 times the speed of the orbiting space shuttle. The refractive index of a medium is calculated by the formula. C is the speed of light approximately 3 10 8 ms v is the speed of light in the medium n is the index of refraction.