you get the blue and red at the start of the mountain path
when you get to the moogles, stiltzkin should be there you can go right to the idol statue or left to fight hilgigars, the guide says come back later becuase you only should have 2 stones
after fighting hilgigars the yellow stone is right infront of you, then go right, you come to a fork, left leads to madain sari, and right takes you to the green stone and an ether, collect it
then go back to the moogles and go right, the idol is much larger than what than the ones the stones used to be in, insert all four stones and you will recieve a moonstone