That is because the spirit of God is in them. That is because Mormon women have been taught to live the commandments of Jesus Christ. And the light of Jesus Christ shines within them, as a result of their loyalty to the commandments of Jesus Christ.
Mormon women are Chaste, and are dedicated to Virtue.
A good idea would be to ask her about social activities that she goes to at her local LDS Church. This would be a fun thing for you to do, and it would be a good way to get to know her better as well.
So that would be my advice as to how to introduce yourself, is to ask about any fun activities that she goes to at her Church as part of Young Adult Activities, and then ask her if she would invite you to go, too.