How do I find the Zodiac Gems?

I have been to all of the doors but don't have the gemstones to open them. I know the leo door is the first one but I don't know where to get the stone.

k... so i figured it out on my own. You just have to be patient :) eventually you will get access to the basements of Vanessa's secret labs. You will receive the stones one by one from a lab worker in the FIRST secret lab that you have access to in the game. The first stone is the leo stone, once you get the ragnarock from that cave you take it back to the lab worker and he gives you the next stone and so forth. You can find a list of all the door locations here
www.chaptercheats.com/qna/android/102999/Alphadia-Answers.htm?qid=10556.

Don't try to fight apocalypse until you are LV 99 and at least have reflect (Dark and Earth element LV 40) for all characters or he will kill you in one turn. Hope this helps!