Mindreading Crayons

You take a box of 4 crayons.
You turn your back and get the Spectator to choose a crayon and show the audience which one they chose and hide the rest and pass the chosen one to you behind your back.
You say you can divine the crayon by touch.
Once done you pass it back and the Spectator puts this Crayon with the rest. You correctly name the colour. Very easy to do!!