Sacrifice is Purple. Void is Black with a blue background. Divinity is white with a light greyish background.
IMHO, I dislike this suggestion because it ruins the Shards' theme of being "Other" (any Elemental can use them) vs. Alchemy's "Element=specific" theme ('potions', which are specific to an element.) I also feel it kind of detracts from the simple design when it's easy enough to tell from the color of the shard/background (Readiness/Time=Yellow, Gratitude/Life=Green,Sacrifice/Death=Purple, Void/Darkness=Black, Divinity/Light=White/Silver, Patience/Water=Blue) and if you managed to win it on the spin or not, unless you're playing in very dim light.