He recalled that his mother paid attention to that sort of thing, enough to have picked up from overhearing her conversations with other women who also paid attention to that sort of thing to know what the woman meant, and have a vague idea of how to answer.
"Her complexion's fairer than mine," he said, stopping a bit out of the way from the woman digging around her inventory. "She's more of a true blonde. Her eyes are green. Sort of. There's a bit of blue to them."
Hey, brain, please don't start trying to overthink why he knows that without hesitation. We're not wanting to go that way.