OK guys - bear with me. I did this little test using 1/16" red fiber optic. Granted it isn't the same size as that used on the front sight but you will get the idea. I cut 2 pieces of equal length and taped them to a paint stick. One end of one optic was dabbed with white fingernail polish. (the left one).
Here are the pic. Pardon the clarity, but it still shows the effect.
Pic 1: Under normal light, polish on end of left optic.