Solid Opal refers to the type of opal where the entirety of the gemstone is natural and no additional layer(s) of material have been attached to the opal layer (such as in the case of triplet opals which are often considered to be of inferior quality, or Doublet opals).

Technically the term solid opal can apply to Solid white (or light) opals, crystal opals, boulder opals or black opals (only Australia variants considered and excluding overseas variants such as Mexican fire opals).

The mining sources of Australian Light Opal include, but are not limited to, Andamooka, Coober Pedy and Mintabie ñ all in the state of South Australia. Solid light opal may also be termed ìwhite opalî due to its whiter colour tone, especially compare to the dark tones of Doublets, Boulder or Black opals. While the flashes of solid light opal might not at first appearance look as sharp or colourful as the aforementioned variants, good quality solid light opals often provides a subtle but engaging play of colours under different lightings and when viewed at different angles.

Crystal opal refers to translucent solid light opal materials that display bright and strong play of colours. Crystal opals are very well sought after; apart from using such material to create ultra-premium jewellery items, Opals Australia also use them for its higher quality solid inlay and doublet range, creating brilliant opal jewellery at a fraction of the cost of a solid crystal opals.