Available in a wide variety of beautiful colors, cubic zirconias are synthetic (manmade) gemstones. Like diamonds and natural zircons, cubic zirconias have a very high refractive index, for maximum sparkle! Sometimes called cubic zirconium, these sparkling semiprecious synthetic gemstones are extremely durable. Shop 4mm loose cubic zirconia stones in jet black and 12 birthstone colors, plus sterling silver and 14kt gold-filled jewelry findings (charms, connector links, ear wires with drop loops) set with sparkling CZs. Occasionally we also have limited-stock CZ beads or other special finds.
These loose 4mm cubic zirconias (CZs) work perfectly with our open-back sterling tube settings and stone setting burnisher set, or can be snapped into our earring prong settings in seconds (see links below). Our expanded selection of silver solder makes it easy to solder the tube bezels onto your choice of sterling blanks or sheet, to create custom pendants, earrings and more.
Cubic zirconias are extremely durable and can withstand high temperatures. They have a very high melting point, so most colors can be fired in kilns with metal clay, a process that would ruin most other gemstones.
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, CZs are cut into faceted gemstones. 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.
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.