The tilaka, or the traditionally red dot the Hindus paint at the centre of the forehead, stands to represent the Third eye. It is most commonly used by women, married ones wear it red, while some unmarried women have it in black. Men also wear it sometimes, though its use among men has decreased.

Well, if you actually want to see a person aura, the easiest way of doing is by looking straight into the third eye spot at the centre of the forehead, the place where the tilaka is painted. If you look straight at that point only, you will be able to catch with the corner of your eyes the aura and its colours. You may see it as uniform layer or quickly flashing colors, or both, mostly depending on how developed are your skills to see auras.

Ted Andrews says in one of his works, "How To See And Read The Aura", that the red dot was originally an invitation to observe a person's aura.