Aw, what a cute little kitty! It's hard to tell breed at that age. It may be a baby Russian Blue or Korat, or a blue British Shorthair. Or it could just be a blue domestic shorthair kitten. Blue is what gray is called in cats . There are many breeds that come in blue, and it's not rare in the domestic population. If you do a search on the picture you might be able to find out if it comes from a breeder's website or just someone's pet pictures.