Justin Talks: Opal Types

In this edition of Justin Talks, we’re diving into the sparkling world of opal types.

Opal is Australia’s national gemstone and comes in a diverse range of forms, each with unique characteristics that affect appearance, value, and rarity. In this guide, we’ll walk you through the main opal types found in Australia, from black opal to boulder opal—and everything in between.

Whether you’re new to the opal world or a long-time collector, understanding opal types helps you appreciate the diversity and wonder of this uniquely Australian gem. Watch the full Justin Talks episode to see each type up close and discover which one might be calling your name.

Black Opal

Regarded as the rarest and most valuable type of opal, and our specialty here at BOD. Found almost exclusively in Lightning Ridge, black opals have a body tone that ranges from N1 to N4, giving them a deep, dark base. This body tone makes the play of color appear incredibly vibrant and bright. The combination of red and blue is rare in black opal because it requires a precise mix of large and small silica spheres—red needs the largest spheres, while blue forms from smaller ones. For both to appear together vividly, the internal structure must be just right, making this bold contrast especially uncommon and highly prized.

Crystal Opal

Crystal opals are defined by their translucency. You can often see through them, which allows for mesmerizing 3D color-on-color effect. Unlike other types, crystal opals can occur across the entire body tone scale—from light to black. Their transparency gives the color play an almost floating quality, and for many, including Justin, crystal opals are a personal favorite.

Black Crystal Opal

These particular gems don’t come around often, and within Justin’s collection, the black crystal opal might just be one of the rarest. With the deep tone of a black opal but without the typical black potch backing, these gems are entirely translucent while still showcasing the rich, vibrant colors black opals are known for. They combine the best qualities of crystal and black opal, and their rarity—paired with a truly mesmerizing play of color—makes black crystal opals especially remarkable.

Dark Opal

Dark opals fall into the N5 to N6 range on the body tone scale. A fantastic alternative to black opals, as they often carry the same vivid play of color but with a slightly lighter background. This makes them more affordable while still offering striking beauty. If you love the bold look of black opal but are after something a little more budget-friendly, dark opals are a great choice.

White Opal

White opal is often what people think of first when they hear the word “opal.” It was the first type discovered in Australia and is known for its milky or pale appearance. Found primarily in Coober Pedy, white opals have a body tone between N7 and N9. Even though it’s more common, they still offer a beautiful play of color, usually soft pastels, and are a wonderful introduction to Australian opal.

Boulder Opal

Unique to Queensland, boulder opals form in ironstone host rock, where veins of opal fill cracks and cavities. These veins are then exposed to reveal their stunning play of color. Boulder opals aren’t graded on the body tone scale like other types, but they can be incredibly bright and colorful. Furthermore, there are different forms, including matrix boulder opal, where color is spread throughout a network of natural cracks, creating distinctive and intricate patterns.

Are you a Lapidary lover or Opal Cutting enthusiast?

Did you know we now have a comprehensive online opal cutting course? You asked, and we listened! We locked Justin in his workshop for weeks on end to capture decades of his professional buying and cutting know-how—now available to you through the wonderful world of online learning. It’s packed with everything you need to know about opal cutting (and then some). Visit our online opal cutting course here.