He seems to be very yellow for a young golden face. I would expect the tail feathers to be white or pale yellow not so strongly yellow. So I would say Olive. The colour varies quite a lot from picture to picture so it is hard to say how strong the blue tint actually is.
Watch when he has his wings open, is it green under the front wing edge, or blue? That is a pretty sure way to tell if your bird is a blue or a green.