So here's a fun game, inspired by my character Jesse.
He can give and take people's hearts. It's not an birth-right, but something that can be learned if you feel enough to want to give away your heart....
Anyway, I imagine Jesse's heart to be a Rose Quartz, something like this [only it glows with the gentle beat of his heart]
The colour of a heart depends on the person, their personality, fears, and the darkness of their desires.
Someone with dark desires would have a heart speckled with black, depending on how evil they truly are. But every heart as a tiny bit of light in it, just as every heart has a little bit of darkness.
I'm tossing around what other hearts would be like now, just for fun.
I think Sky's heart is Opal, something like this:
She's a relatively pure individual with a variety of love and fears and her heart is coloured as such.
Eyez would have a heart much more like this:
See the evil, but speckled with light, because he's always tossing up between the two, but so far, I think evil is winning
Blake's heart:
He's divided between the dragon, the cat and his own desires. When does the dragon's desire to hurt people end and his own begin? Not to mention how generally sad he is. He's a little emo XD
Any suggestions for your own character's hearts?
I tend to think of gemstones but there's no reason they can't be silver, or glass...
The Colour of Your Heart
Dark black and red, like him to show the cruelty and demonic nature.
Dark and blood covered. 
