Simon,
thanks for the reply. The thing is I had already bought the glue for this job never having used it before. But in the end I did a test piece and there doesn't seem to be a problem at all. At the time of writing this I have glued up 15 rings in Ebony and I'm pleased to say you struggle to see the joints, although I am using Titebond 3 and not 2 as previously stated. I too have used dye in glue before now but you have to be a bit careful that it doesn't stain the wood before you clean the glue off.
Regards
John