I'd vote sky blue or silver (PED of blue). If the eye color is ruby or pink, it'd be a silver. The face, from the picture, looks to be lighter than the rest of the body color, that'd be an indicator of silver IF it had dilute eyes. Google it, it isn't related to the silver gene, either - I'm talking about a self color (if all that wasn't confusing lol). Dove is a warmer color, usually, and mink is a cooler medium brown, much darker.

http://www.afrma.org/ratselfs.htm <----- CTRL+F sky blue, it's on there! Mink as well for comparison.
http://www.afrma.org/ratsilvr.htm <------ Silver blue (different from the silver I mentioned above).


Adorable, either way!