White topaz and white zircon are both popular and affordable white gemstones, but there are some key differences between the two:
Composition: White topaz is a silicate mineral composed of aluminum, fluorine, and silicon, while white zircon is a mineral composed of zirconium silicate.
Hardness: White zircon is a harder gemstone than white topaz, with a hardness of 7.5 on the Mohs scale compared to topaz's 8.
Brilliance and Fire: White zircon has a higher refractive index and dispersion than white topaz, giving it more brilliance and fire (the rainbow-colored flashes of light that can be seen in a gemstone).
Availability: White topaz is more commonly available and less expensive than white zircon.
Treatment: White zircon is often heat-treated to improve its color and clarity, while white topaz is typically untreated.
Overall, white zircon is generally considered to be a higher-quality gemstone than white topaz, with better optical properties and greater durability. However, white topaz can be a good alternative for those who want a more affordable option that still has a white color and some sparkle.