Red cabbage makes blue water, will prob. need vinegar as a fasting agent. Yes, beet juice makes nice red eggs. Blueberry juice makes blue eggs too. Turmeric or saffron will make yellow....oh, what did I use for green....seems like it was minced raw parsley or some other green herb.....but maybe I mixed the turmeric water and the blueberry water. It's been a LONG time since I did it.

I did something like 12 doz eggs this way, for an SCA feast, but I peeled them first. The white takes colour better than the shell.