Gems Stones

How is it that people from India are gems and stones in the front?
I wondered, and how to make it stay there?
there is a small hook embedded in a metal base on which the Gem is set.this hook is in the bottom of the bem. a black thread and yarn soft works its way through hook and serves as a link going back cords over your ears and knotted at the nape of the Uruguay Round under the hair. seems as if the gem is jus stand on their same.