is my gray cat Russian Blue?

Question

Magic   I always thought my gray cat Magic, who I found as a stray young adult in 1999, was a domestic shorthair, but recently I posted this picture of him on Facebook and one of my friends called him a Russian Blue.

I was curious if he actually might be Russian Blue (or at least part). He's all gray (when I first found him his fur had a silvery look that has mostly gone away), his eyes are yellow with a hint of green, and he has very subtle white stripes on his tail and hindquarters.

Is there any way to tell for certain?

Answer
I do not think he is a russian Blue...the head structure is not correct, nor is having any type of strips or barring on the coat.  His eyes would be brilliant green only.
So I strongly doubt he is Russian Blue.  Often when people see an all gray cat they think it is Russian blue.  There are gray cats randomly bred in nature.
He is a very pretty cat however, and very lucky to have found such a good home