Zircon comes closer to resembling Diamond than any other natural gem. Its strong luster and intense fire gives it a real sparkle that is comparable to Diamond. However, its popularity is somewhat diminished by the fact that it is often perceived as an inexpensive Diamond imitation. Colorless Zircon is easily distinguished from Diamond by its strong double refraction and lower hardness. Colorless zircon is known for its brilliance and flashes of multicolored light, called fire. These zircon properties are close enough to the properties of diamond to account for centuries of confusion between the two gems.