Lab-created cubic zirconia (CZ) can be used to imitate the appearance of many gemstones. Although most well-known as a diamond simulant, this material can be manufactured in different colors, like this teal, star-cut piece. However, CZ’s properties still differ from those of other gems, so gemologists can usually distinguish them. Most notably, CZ’s specific gravity far exceeds that of most gemstones. Photo by humanfeather. Licensed under CC By 3.0.