hands have a different color usually because we use them for everything. any time you are active in one part of your body you will see yellow or yellowish green/blue, on the forearm for guitar, shins for running or soccer/football (other than the US) umm a lot of yellow on hands if they do crafts or sew. if yellow is around there head then they are a thinking and analyzing type.

also i see collars on the back of the neck if the person is the type that likes to support the worlds problems, being there for people or letting others happiness come before there own.

if they have a swirling black and red and a fierce look in the eyes then someone has died, if they have the black and red swirls and spikes but the eyes look either normal or empty then they are very very emotionally in pain.

I find that most peoples aura is purple when they are mostly content with the world.

pink if they are in very good terms with there ego(rare) being tolerant and accepting things easily. very little or no jealousy, greed, or judgment on others.

if there green then their healing.

if there blue then they are at peace but pale blue is a boredom or sadness.
I don’t see many of the other collars to well. I know that the really bad ones are dark red black brown and grey. There are many interpretations and its hard to see the exact shade sometimes.