Buying Boulder Opal? Here’s 10 Things You Need to Know

In the market for Boulder Opal? When it comes to buying such a unique stone, you’ve likely got important questions. You’ve come to the right place! Read on as we highlight 10 important facts to consider when buying Boulder opal.

1. What is Boulder Opal?

Boulder opals are a unique stone predominantly mined in Australia, and have a dark base color peppered with bright neon colors. Of all the classes of opal stones, Boulder opals tend to be at the higher end of the spectrum, next to black opals. When comparing black opal to Boulder opal, you might think they look similar. However, a closer inspection will reveal that black opals have an intensely dark base color, while Boulder opals have a dark brown, or even light brown base. Which is exactly why...

2. Boulder Opal is Not Black Opal

Boulder opals are sometimes confused with black opals because they contain a similar dark base color. Just because they are dark does not mean they are Black opal. Black Opal is a term reserved only for Opals that come from Lightning Ridge and have a body tone between N1 and N4.

3. Are Boulder Opals Brown or Black?

When Boulder opal is cut from the ironstone, the cut is precise to display the ironstone as the color base of the stone. This color is a delicious earthy brown color and it helps to highlight the gorgeous color of the Opal.

4. What Color is Boulder Opal?

Even with the dark base color, the beauty of Boulder opals is that they reflect an assortment of vivid colors. Most commonly, the base color and most dominant color coming through is brown. However, an intricate pattern of colors shine from the stone, including bright blues and greens, fiery yellows, oranges and reds, and even purples! In fact, the best level of Boulder opals display a vivid spectrum of colors. However, there are some Boulder opals that have a milky base. That’s because there’s an additional layer of sandstone underneath the base color that is lighter. This can create an effect of an overall lighter colored stone.

5. Where Does Boulder Opal Come From?

Boulder opals are mined from the ground, where large ironstone boulders form veins of unique and colorful opal in their cracks. These large boulders are mined in Outback Queensland. The rich opal fields of Quilpie and Winton are geological meccas brimming with ironstone.

In fact, Australian opals have an impeccable reputation because of the dry climate. This means that over time, opals become more dry and resistant to cracking. Of course, there are other sources where Boulder opals are mined, including the USA, South America and Africa. Still, the Australian ironstone has a reputation for providing high-quality Boulder stones. 

6. Will Boulder Opals Crack?

That isn’t to suggest that every Australian Boulder opal is perfect. Fortunately, if Boulder opals are prone to cracking or crazing, it’ll happen when the stone is being cut and before it reaches the retail market. Of course, you should always be vigilant when buying Boulder opal, and only purchase from reputable dealers like those on Opal Auctions.

7. What is Good or High Quality Boulder Opal?

Because we’re dealing with a colorful stone, the best variations of Boulder Opals will have a deeply saturated dark base contrasting bright, clearly defined colors. The greater the contrast between the base and the accent colors, the higher quality the stone. Still, each Boulder opal has its own unique color palate, and you might be drawn to a quality of Boulder opal that’s not necessarily as high as others, but has a color scheme that appeals to you. When buying Boulder Opals, it’s best to follow your eyes because they’ll tell you what you like best.

8. What is the Best Shape of Boulder Opal?

When browsing Boulder opals, you’ll come across a variety of unique shapes, often exposing the intricate ironstone from which the stone was cut. Commonly, Boulder opals follow the traditional shape of Opal, which is an oval stone featuring a high dome. However, this particular shape produces a lot of waste as most of the rough stone gets cut away. That’s why naturally shaped opals have grown increasingly popular. Not only is it more efficient and economical to use raw stones, but it looks unique and gorgeous. Most often, you’ll find Boulder opals available in free form shapes, but they can also still be found in the traditional oval shape.

9. What are Boulder Opals Worth?

Valuing a Boulder opal is a complex process, and several factors must be assessed including the pattern, brilliance, base color, size, play of color and more. First, an opal must be examined, then a carat size will be determined, and from there the stone can be valued. Black opals are the most expensive type of opal, and can cost thousands of dollars per carat. In general: the less visible the ironstone, the higher the price tag.

10. Where Can I Buy Boulder Opal?

Bottom line, there’s a lot to remember when buying Boulder opals. With this information in hand, always buy from reputable jewelers who is willing to answer all your questions and work with you to find the right stone.

Boulder opals are a unique and gorgeous stone, each with its own play of color, shape, and story.

Ready to unveil the perfect stone? Browse our wide collection of beautiful Boulder opals.

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