Beautiful!!
As Janine said, they aren't supposed to have a lighter under fluff, or they are considered blue. However... I do think there could be some exceptions to this. In the black thread a while back, one of the girls who is breeding black X black was getting some with lighter fluff, but it wasn't too much lighter and she knew exactly what the breeding behind the bird was. I don't remember who it was now. But it isn't ideal for a black bird, but I think it can happen. I would breed him and see what you get, he has incredible type and a great crest! If his comb is dark, don't worry too much about his wattles being on the redder side. I KNOW that isn't desirable, but with careful breeding, it can be worked out. I used a roo last year that had a bit of red to his little wattles and it didn't pass on. Gosh, even his wings look really, really good here.
They may be... or they may not be. I ended up with some really dark blues, BUT their underfluff is so obvious and I think they are obviously blue (to me). I really like the darker blues. Mine look nearly black and I've had no troubles showing them. This Spring I had Art Reiber-- who is a very well known judge (and will be at Nationals) judge my dark blues and he knew right off they were blue. In fact, he told me I nearly won best of class and if her crest had been just a bit bigger, she would have done it. He kept going back to her cage over and over. Sigh. Here he is with my Blue that he really liked. I love this picture of him, he doesn't miss a thing.
He never said one word about her being too dark. And clearly-- she is a very, very dark Blue. She has thrown lots of Splash-- in fact, mostly splash babies. But her blue offspring is just as dark as she is.