User blog comment:Kogath/Monster Hunter XX Discussion/@comment-26532315-20161027164501/@comment-2194133-20161028043755

Here in this Monster Hunter 4 Ultimate gameplay and in this Monster Hunter 3 Ultimate gameplay we can see clearly some bluish tint on Black Diablos. Again, I mainly bring it up because this is the only real connection I can find between Diablos (who is normally sand-colored) and the color blue.

But yeah @Kaiser G. Saw you are right: MHP3rd Black Diablos does have reddish rather than bluish tint for some reason.

Could be something, could be nothing, only time will tell.