The accomplished orb photographer Candice Wong has recently published some astonishingly colorful orb photos on her Facebook feed. You can see them here (you may have to log in to Facebook first). Very many of the orbs that she photographs have a yellow-greenish color in the center. I don't get such a thing (although I do photograph many purely yellow orbs, as shown here).
Candice's orb photo here looks very much ones I have taken, in that we see a blue color, an outer ring, and a central dimple. I get all three of those features very often, although when I get this central dimple feature it is more subtle.