(I copy pasted your comment XD)

Gems live in villages by big mountains and/or rocks and rivers. They are kinda hard to find and if you find one it depends on your personality on what you'll do.

You can either take pictures and let them continue living.

You can capture one and make it cry crystals which you can sell for 50 up until 400

Or

You could capture as many as you can and sell them for 300 up until 2 million. The rare ones are very expensive, like a hybrid between a Diamond and Jade.
That's what happened to this particular village. Three men found them and started to take off roofs on their houses, taking every Gem they found this included the Crystallika triplets and Rae and their loved ones. They were put in seperate golden cages and loaded into a truck with 15 other Gems.

CICCIChan