He doesn't really need to say it. Gems are so rigorously pigeon-holed into certain jobs based on their gem-type alone that Peridot easily goes there herself. She opens and clenches her fists repeatedly, plainly wanting to argue that point but finding herself unable to do so.

"What if something goes wrong with him?" she says instead, looking back over at Childermass. "I'm not exactly knowledgeable about human medicine!"