How can I tell the difference between an aura and an after-image?

Q: When I am trying to look at someone's aura I usually always see like a fluorescent blue but its like a little tiny layer....nothing big and flaring....but then sometimes I will look at someone and they will have a different color aura like green and then I will look at someone else but they will have the same exact color and then I realize they are both wearing pink....since I am still a beginner and can barely see two layers of the aura, how can I tell if its just the color radiating off of the clothes color or the actual person's aura?

Thanks so much!

Eva's Response: Ok so the best way to test if you're seeing an aura or an after-image is to close your eyes. Can you still see the color? If so, it's an after-image and not an aura.

If it is an aura you're seeing, you will not be able to see the color anymore when you close your eyes.

You also might be seeing the opposite or complementary color. Think of this as like a shadow that the eye sometimes picks up when you see a color. A quick simple list of colors that are opposite to each other are:

Red / Light blue
Pink / Green
Dark blue / Yellow