Violet had been lost in thought, brooding about the increasing strangeness in the castle, but caught herself after a short while and began jotting down notes about the objects.

Stone--hardest to transfigure, due to its weight and density
Leaf--in between; it's light, but also a living thing and more complex
Ice--easiest--though heavier and denser than a leaf, if it gets above freezing, it practically transfigures itself