Blue is a reasonably new colour and came to the UK via my hamstery in November 2017. Originally discovered by a breeder in Finland, this is now more widely bred in the UK and mainland Europe.
Blue is a non lethal recessive colour and thought to be the first self colour in Roborovski. Breeding is still in progress to determine exactly how this gene works as we still need to breed it without the pied pattern.
Theoretically blue should be a dilute gene that exclusively dilutes black pigment. A blue agouti would be needed to show this. You would have a blue/brown animal with eyebrows etc. A self blue should actually be a dilute black and everything we’ve seen so far suggest it would not have the eyebrow or other white face markings of the agouti. Despite having darker hamsters thought to be black in 2018, all of the pups bred so far have either been normal agouti (and pied) or self blue pied.
It should be possible to breed a self black, self blue and agouti blue to which we could then breed red eyed blue and husky blue. Until we see a blue agouti and a self blue without a pattern we won’t know for sure what would be possible.
This dilute gene is not yet recognised and is not ready to be standardised in the UK. Hopefully, with now more breeders taking this on in the UK we will see this change soon.