I am stuck in the lava room of Sky Keep. I managed to unlock three areas with gems by dropping bombs into baskets. First was one near the entrance, second was behind some foliage, and third was down a sand slope. I found that if I shoot each of the three gems with a bow and arrow, or use the beetle, they turn gray.
However, nothing happens after I shoot all three. They turn pink again. I thought it might be on a timer, so I tried to shoot them all really quickly, but that didn't work. I thought there might be a forth gen beyond a barred door, but if there is, I don't know how to open it.
What do I do with these three gems?