It is a fun game, the concept is original and I enjoyed the mechanics. Some (I hope useful) feedback:
It is a bit frustrating that I cannot insert gems while i'm making a jewel, so i have to deselect all of them and insert it... I think you could allow players to drop gems while making a pattern
The instructions could be with images instead of text, it would really benefit this kind of game. Or maybe a short tutorial that guides you with arrows that tell you where to click?
Overall a really great job :D