OK, this is a good one. From the picture that is posted, you say that it is neither the ruby green or the burtoni. I have scoured my resources and can't come up with anything. It has coloration that is similar to the burtoni, but has blue where a burtoni should not. As for it being a ruby green, it does no have near enough green on it. As the Rubys begin to color, the green is very prominant and never really takes on a blue tint.
The tail is a very tricky part. Te me, it looks as though there could be red that shows up on the tail eventually. Looks to be a young fish, 1.5-2.5".
I would have to say that this guy is most likely a hybrid. If you could find a picture with better coloration or when it gets older, that might help us get to the ID a little better.