Opals are one of the most beautiful gems ever! Their iridescent colors have captivated people for centuries. Today, opals continue to enchant with their array of colors and sparkling glow. But can these precious stones really be valuable? That’s what many people wonder when they see an opal for the first time.
Boulder opals are natural gemstones that come from rocks. These are also known as flash opals because they display a brilliant flash of color when they catch the light. Because of that, they’re highly sought after and can sell at high prices. On the other hand, not all boulder opals are valuable and there are many different factors to consider before making a purchasing decision. In this article, we will review everything you need to know about boulder opals so that you can make an educated decision about whether or not it’s worth your money.

What is a boulder opal?

Boulder opal is found in cracks, crevices, and cavities. Silica from dissolved sand trickled down cracks and crevices in ironstone boulders and the silica precipitated out of the solution. Boulder opals are also referred to as “flash” or “fire stones” because they have a brilliant flash of color when they catch the light. Boulder opals can vary in color from light yellow, orange, red, brown, green, and more. Sought-after boulder opals are found in Australia.

Differences between boulder opals and other opals

Boulder opals can be very similar to other types of opals, but there are also some important differences. Boulder opals are typically found in small cavities, called joints, and on the surface of boulders. They have a more irregular shape than most types of opals. Another difference is that boulder opals don’t usually have any inclusions or watermarks when they’re mined. Finally, boulder opals often have a rough surface with a rough fracture line that will sometimes produce a rainbow effect. 

Factors that determine the value of a boulder opal

Boulder opals begin as small crystals that form in a host rock. They are embedded in rocks like granite or diorite and can be found throughout Australia, Mexico, and the United States. The type of rock, where they’re located, and their color all affect the value of boulder opal.
Some stones that are more valuable than others include:
-Opals with blue, brown, green, or black colors
-Opals with a high water content
-Opals with fire patterns


It’s difficult to pinpoint an exact value for boulder opals because these stones vary so much in size and color. However, you can expect to pay a high price to own one of these beauties. They are valued based on their rarity and beauty but are not as valuable as other types of opals such as precious opal or black opal.