Cubic zirconia can look somewhat similar diamond when brand new. However, cubic zirconia is not as refractive or sparkly, having a lower refractive index (2.15) than diamonds (2.42) and a much lower refractive index than moissanite (2.65). The biggest issue with cubic zirconia is durability. In as few as three months, cubic zirconias will become cloudy and dull. They tend to get easily scratched and this further contributes to the deterioration in their appearance. Cubic zirconia is a great choice for costume jewelry that you may want to wear once or twice a year but its lower durability and longevity make it a very poor choice for everyday jewelry. This is one of the biggest reasons you never see cubic zirconia set in gold or platinum - the stone's lack of durability means it is not worth setting into costly precious metals.