Diamonds?
Everyone loves me, but only the lucky ones can have me.
Only the rich can afford diamonds but everyone loves them... Girls best friend i have heard!
I'm indestructible, but only with my own family.
Nothing can scratch a diamond apart from another diamond
Many got killed because of me, serpent being killed to get me but no success until today.
People fight over diamonds and have killed over them and you can get them from snakes... Or so i have heard!
I live underground, but can be seen on earth.
Not totally sure on this one, but there are mined from underground, and can be seen in the earth (dirt).