Zircon is a mineral belonging to the group of nesosilicates and is a source of the metal zirconium. Zircon is a double refractive material with a refractive index of 1.93 – 1.987 and a hardness of 6.5 - 7.5 on the Mohs scale. This Blue Cambodian Zircon weighs 6.59 cts. and measures 13x7x6 mm.