Black opals are the rarest and most valuable type of opal, known for its dark body tone that highlights its vibrant play of colour - the brightest of any opal.

The term 'black opal' doesn not mean that the stone is completely black, rather it has a dark body tone caused by trace elements of iron oxide and carbon.

Black opals are primarily found in Lightning Ridge, NSW. Because of its relative scarcity compared to light and boulder opal, it tends to be more expensive, given equivalent colours, clarity and patterns.

Boulder opals are defined by their natural matrix or "boulder" which gives the stone its distinct appearance.

Boulder opals are formed as patches or seams attached to the host rock and are often cut with ironstone left on the back. They can appear either black or light depending on how the stone is viewed from the surface.

Boulder opals are mainly found in Western Queensland and are suitable for those looking for a representation of opal as they occur in nature.

Crystal opals are renowned for their translucence and transparency. Light easily passes through the surface and into the core of the stone, giving them mesmerising iridescence.

Crystal opals are formed by the slow precipitation of silica gel from groundwater over millions of years. This process gives them a translucent body, which enhances the visual impact of their exceptional play of colour.

Crystal opals are found in Lightning Ridge, NSW. Stones with a broad spectrum of bright, intense flashes of colour are highly prized and typically command a higher value in the market.

Fire opals are infamous for their fiery spectacle of red, orange and yellow hues. These opals can often be referred to as "Mexican fire opals" because they are primarily found in Querétaro, Mexico.

Fire opals are formed in volcanic environments when silica-rich fluids seep into volcanic rock and harden over time. This unique formation process gives fire opals their unique and vibrant colors.

Although usually not showing any play of colour, highly valuable pieces can exhibit flashes of bright green.

Doublet opals are created by bonding a thin layer of precious opal to a backing material, usually a dark-coloured ironstone. This process enhances the stone's appearance by providing a darker base to accentuate the opal's vibrant colours.

Doublet opals can offer a more affordable alternative for those who want to enjoy the beauty and brilliance of opal jewellery, while still displaying striking play of colour. However, it is important to note that doublet opals are not as durable as solid opals and require extra care during cleaning and storage.