Available in a wide variety of beautiful colors, cubic zirconias are synthetic (manmade) gemstones. Like diamonds, cubic zirconias have a very high refractive index and are visually stunning. Unlike diamonds, CZs are relatively affordable. They are also very durable and can withstand high temperatures. Cubic zirconias can be fired in kilns with metal clay, a process that would ruin most other gemstones, because they have a very high melting point.
The greatest challenge for scientists wishing to create CZs was making a crucible that could withstand the temperatures needed to melt and hold zirconium feed powder. In the 1970s, scientists in the U.S.S.R. designed a "skull crucible" that allowed commercial production to take off.
The gemological properties of CZs vary by manufacturer due to variances in the type and amount of stablizer used to make isometric (cubic) crystals. Different oxides are added to create colored cubic zirconias. After controlled annealing to ensure the flawless crystals are stable, the CZs are cut into faceted gemstones. Cubic zirconias are now the most common diamond substitute, and the highest quality CZs can often fool even trained eyes. Bead quality CZs are not likely to be mistaken for diamonds, but they are beautiful all the same.
You can safely clean your cubic zirconias with any jewelry cleaner or detergent. Be sure to rinse well to avoid leaving a residue that would dull the gem's shine.