Cubic Zirconia is a very inexpensive simulated Diamond and an excellent alternative. Although mostly seen in its white or colorless forms, CZ (as it is commonly known) is also available in a wide variety of colors. Nearly as hard as Ruby and Sapphire, the optical properties are high and CZ has good brilliance. Despite its near stranglehold on the simulant Diamond market for the last two decades, it now has more competition from other man made gemstones such as Moissanite. 

Colored Gemstones are now the largest growth sector in the jewelry business