Tears are Gems of the Soul

Hobbits have a hidden ability- when they cry, their single tear crystallizes into a colored gem. Bilbo hasn't felt emotion since the death of his parents decades ago, but being dragged on the quest and thrust into close contact with thirteen dwarves has awakened his emotions with a vengeance. Can he keep his secret from those he's becoming close to? Very slow build Thorin/Bilbo.