I think he is still rather young, he seems awful small compared to Spot so I think as he grows his coloring with come out more. He has a few more blue spots on one side today that I noticed. Also the orange along the top of his head and his fins below the bluish green is starting to show more.
I was looking a pics of Grizzles and Marbles last night and seems to look more like them than any other betta color. Along the fact, he is becoming quite the shimmer. I was watching him swim around in the sunlight that was coming through the window and he was shimmering away.
Yes, I couldn't resist calling him Jack... Get close enough to the bowl and he swims right like "Why hello there"