For me the pretty appearance of these eggs is flawed by the fact that I find them rather hard and indigestible. However, some people love them, and they are the traditional accompaniment to Ful medames.
Hard-boil your eggs as described.Gently crack them all over with the back of a spoon so that they are covered with hairline cracks. Make a marinade of strong tea mixed with rose water and vanilla or cinnamon, and bring to the boil. Simmer the eggs in this mixture for 15-30 minutes, depending on how dark you want the colour to be. Allow the eggs to cool and then shell them.