When it comes to choosing the best pick among Semi Precious Gemstones gemstones, Opal is known to be a popular choice!Physical properties of Opal include its hardness, gravity, fracture, cleavage, etc. For any gemstone crystal, Opal Optical Properties are responsible for imparting various physical properties to its structure. Knowledge of these properties is equally important to gem-cutters as well as to consumers. Opal cleavage is nothing but the plane across which the crystal splits during cutting. Opal cleavage is None,and specific gravity of Opal is 1.98-2.25.
The physical properties of Opal, in fact, are imparted by the chemical composition of its individual molecule. The reactivity or inertness of the crystal is solely governed by its chemical structure. Chemical composition of Opal is represented by SiO2 · nH2O.