Childermass is no stranger to the feel of magic, and as such it is not only the look of the charm itself, but the spell put upon it that catches his attention. He watches the other man with the phone, casually assessing, not particularly caring whether he's being obvious about it or not, before speaking up after the other man's done texting.

"That's an interesting charm you've got there," he says, with a pointed look. He knows what it is, and while he's not certain of the magic exactly, he'd be curious to find out.