How do CZ gemstones compare to diamond gemstones visually/in person? It looks like CZ has a lower refraction index but higher color dispersion vs. diamond, so that seems like it would still result in an attractive gemstone. The main disadvantages seem to be slightly lower refractive index (so less internal reflection and brilliance?), lower hardness (disadvantage for the gem getting scratches - possible advantage for not scratching your sapphire glass watch or smartphone camera lens?!) and higher weight.

edit: seems that moissanite (silicon carbide, perhaps unsurprisingly) is another diamond-like (though hexagonal crystals vs. cubic for diamond or CZ) gemstone that is actually harder than sapphire and less prone to fracture than diamond.