Gem object
Added gem.js and some testing sprites
Sparx searches for gems every step, if it finds some, it will stop following spyro and it'll move to the gem to pick it. The gem then jumps to spyro.
Spyro searches for gems every step, if it finds some, it should destroy it, but I don't know how to do it properly. I'll let this to you sheep.
The gem collision with tarrain was a bit glitchy, the gems slided down all the way on the line, even if it was only tiny cliff. Added some wuick fix, maybe it could be done better.
Added some Gems

Merged with your edit.
Added gem.js and sprites for the colors.
I don't know how to integrate the colors with your editor Sheep, I guess it's up to you.
Sparx should pick the gems and when spyro collides with them, they disappear.
TODO: add gem count, remove gems from array