Gemstone Heart

Gemstone Hearts were “the soul of a Clockwork Cherub's processing unit”.

The type of gem used could supposedly affect the Cherub's personality. For example, while most Cupids had rose quartzes for hearts, Amadeo-378 was rumoured to have a five-point diamond, allegedly accounting for his unusual intelligence and military prowess, (PROSE: The Green Gorillas) and Pessimist-242 apparently had a simple lump of coal for a heart, matching his dour personality. (PROSE: The Toymaker's Labyrinth)