Cubic zirconia (CZ) is one of the most popular and well-known materials in the jewelry market. It is a synthetic form of zirconium dioxide (ZrO2) with added yttrium oxide. Originally developed by Soviet scientists in the mid-20th century for use in electronics, optics, and medicine, its stunning optical properties — such as brilliance, transparency, and dispersion — quickly caught the attention of the jewelry industry. CZ is now widely used as a diamond simulant and comes in a variety of colors, color changing options and opaque shades with increased hardness (9 on the Mohs scale).