I like the environment. I'm not sure if just having to guess which gem is real is all that fun though, perhaps giving the player more clues to work out which one is real would be more fun. But it looks nice and the platforming controls feel good :)
Also just wanted to mention a small technical issue. A lot of unreal engine games have this problem so it's probably just a setting you have to change (I don't use unreal) but if you have a VR headset plugged in, the game will try to launch in VR. I had to use a small workaround to play this but it would be good to look into making the game not VR.