The opal is was said to have all magical powers because of all the colors is contains. The red of the ruby the green of emeralds, golden light of topaz, the purple of amethysts. Opal is supposed to strengthen sight, cure eye diseases, and make the wearer invisible. It is said to protect against contagious diseases, ease sadness, and pale in the presence of poison and for all you blondes out there opal is supposed to guard the color and life of blonde hair.
Opals are one of the few mineral gems considered to have no crystal structure, they are amorphous.
It is made up of tiny sphere of either amorphous silica or cristobalite. The difference is that cristobalite has a tetragonal crystal structure. These balls are arranged in a grid like structure and it is this arrangement that causes the play of color. The colors we see depends on the size of theses spheres. Smaller spheres diffract shorter wavelengths such as blue, while slightly larger ones diffract longer wavelengths causing us to see green as well as blue.