Zirconium oxide is in the monoclinic or triclinic or whatever crystal system when it crystallizes in nature. However, they take and heat it up and it changes to the isometric aka the cubic crystallization. Then the stabilize it with calcium and/or something else and it might be neodymium? Then they take it down and it is this beauteous crystal they can cut for gems. What I want to know is 1) What exactly do they add and why or how does this stabilize the crystal so it doesn’t revert at the phase change temperature, and 2) is the zirconium in the gems, or for that matter in the refractory crucibles they use zirconium oxide for, metamict? Because I know zircons the gems tend to be to some degree metamict, meaning they really have no crystal structure because of radioactive bombardment from and here comes question 3) from what? Also I forget what the gem zircons are made of but it isn’t zirconium oxide, I don’t think. 4) What is it?