Lay out your jars of colored teas. Decide what combinations of alum and color modifiers you want to add to each.
Use 1 teaspoon alum per jar AND/OR 1 tablespoon of liquid modifiers (vinegar, lime juice) OR 1 teaspoon of any of the powders (citric acid, cream of tartar, tartaric acid). Mix well.
Gently add 1-2 boiled and unpeeled eggs to each jar. Refrigerate overnight.
The next morning, gently remove each egg and lay on a wire drying rack. If you’re satisfied with the coloration, you can stop here.
Alternatively, return the eggs to their respective jars, and allow to steep again for up to an additional 12 hours.
Remove the eggs gently and dry completely on a wire rack.