A cubic zirconia or "CZ" is the cubic crystalline form of zirconium dioxide. The resulting synthesized material is hard, visually flawless, and typically colorless, but may be manufactured in a variety of different colors. Due to it's inexpensive cost, durable wear, and very close appearance to a diamond, the synthetically made cubic zirconia has been the most economically and gemologically important competitor for real (mined) diamonds since the mid 1970's.
Lab created or lab grown diamonds are not the same as cubic zirconia. The following will provide more detailed information regarding the major differences: