White diamond telling Steven he's "acting like a child" doesn't make sense because not only do gems not age, but white had also never been to earth before that episode, so she simply could not have known what a child was, let alone how they behaved.
When Yellow Diamond is yelling at and wrestling Blue Diamond, red capillaries are seen in her eyes. But since gem beings forms are made of light, the don't have circulatory systems, and no capillaries would be evident.