Opal is technically a mix of two different minerals, Cristobalite and or Tridymite. This combination reveals a mineral combination which is world renowned for its beauty and has a hardness of 5.5 to 6.5 on the Mohs hardness scale.
Opals can come in a variety of colours from clear to white, blue, pink, red and rainbow. The colours are due to slight mineral inclusions and the diffraction of light within the mineral itself. Opal can often appear to have a fire of colours within it, all sparkling and glistening in the light.
These stones are often considered to be bad luck. This is not the case, they are simply mood enhancers. Wearing Opals when you are in a good mood will bring about great results, wearing opal when in a less than positive mood will often yield unfavourable results.