CZ (Cubic Zirconia) stones are lab-grown gemstones, designed to fit in our claw settings. They come in a variety colours and sizes – 2mm, 3mm, 4mm, 5mm, 8mm and 10mm.
Cubic zirconia (CZ) is the cubic crystalline form of zirconium dioxide (ZrO2). The synthesized material is hard and usually colorless, but may be made in a variety of different colors. It should not be confused with zircon, which is a zirconium silicate (ZrSiO4). It is sometimes erroneously called cubic zirconium. (Wikipedia)
CZ’s are an inexpensive diamond alternative.