Optical Properties of Opal are its behavioral responses towards light. While few optical properties can be identified with naked eyes, other require special instruments by the gemologists to identify them. Opal optical properties like luster, clarity, refractive index etc. are used to determine the non-destructive methods during gemstone identification and evaluation.
Opal luster is the quantity of light the crystal reflects when light is incident on it. Opal which is commonly found in Yellow, White, Red, Brown, Blue color, is Translucent, Transparent and Transparent to translucent in nature. It possess Pearly and Vitreous luster.