shine in girls eye

i am sure that most of you have seen or heard that something in the eye.
when she meets him there is a unique glow in a girl's eye when she is truly likes the guy irrespective of being in a relationship with him or not.
also there is a certain kind of expression on the face.a more visible thing is that she or he will find oppurtunity to glare at that person.
these things are not in our control.
how much importance should one attach to this.is it the ultimate sign??
can love be assumed on basis of this.

I wouldn't say it is out of our control since it can be manipulated. The importance aspect is high but I wouldn't say it is the ultimate sign since there are other, much larger signs. Love can be assumed on the basis of how you feel, so in a sense, yes it can be assumed on the basis of that.