War League Gems + Blessings

I’m a bit confused as to how the gems + blessings work in the war. 

If I’m in a league that has 4 war blessings + 1,500 gems as a reward, what actually triggers this reward?

Is it given each time you keep your place in the league (i.e. not in the green “advance” or red “demote” zones)?

Is it given each time you are in the green zone and advance to a higher league?

Are rewards also given when you are demoted to a lower league? 

I’m sure I read about how this all works but have been unable to find the postings.

You get it when you stay in your league at the end of the season. If you get promoted up or down you get the prizes for that league