Opal displays a particularly interesting optical effect known as ”play of colour”. Opals structure holds the key to this amazing display; being formed from micro spheres of silica between 150 and 300nm in size, light hitting the gemstone is diffracted by these spheres resulting in Spectral colours being reflected. opal is named for this phenomenon, the Greeks called the gem ”Opallos” which means to see colour change. Opal is primarily sourced from Australia with new and upcoming locations such as Ethiopia gaining momentum. In ancient times it was believed that Opal had the power to prevent fair hair fading or darkening and Opal stood as a symbol of fidelity and assurance.