Boulder Opals – Strength and Beauty

Jewelry Care
Opal Gems

Gaze deep into an opal and you’d be hard-pressed to disagree with the ancients that you were looking at a rainbow trapped within a stone. Its spectacular shifting hues (known as play-of-color) give it a sensational vitality that is not replicated by other gems. Unfortunately, for jewelry lovers, the beauty of the opal comes at a cost – these stones are delicate and need to be treated with some care. Not all opals are created equal, however, and if you want to enjoy all of the magnificence of an opal but with less chance of damage, then you should definitely look at boulder opals.

They come from a land down under…

Today it’s estimated that around 90% of the world’s opals come from Australia. The first discoveries were made in the middle of the 19th century, but it was not until the 1880s that a mining boon took off and Australian opals started to appear on the world market. So spectacular were these Antipodean gems, with a fire never before seen, that their European rivals spread rumors that they were not genuine. The ruse didn’t work and a few decades later, unable to compete, Europe’s only source of opals for millennia (the mines in today’s Eastern Slovakia) closed for good.

A bit about black opals

The opals that caused such a stir on the international market were black opals from the evocatively named Lightning Ridge in New South Wales. They are highly valued for their intense play-of-color and vibrant hues which gleam against a dark background. These stunning stones come from either ‘nobbies’ (nodules of opal) or ‘seams’ (horizontal opal deposits) within sedimentary rock. Once extracted the opal is usually cut into oval-shaped stones with a domed cabochon top.

Boulder opals – the name says it all!

Boulder opals are, as their name suggests, found in boulders made from ironstone. The opal occurs in thin ‘veins’ or ‘pockets’ which makes it impossible for cutters to create the pure opal, domed-shaped cabochons preferred by most buyers. Instead, part of the host rock is left behind on the gemstone which typically will have a flat or only slightly domed surface and possibly an irregular shape. Crucially, boulder opals are defined by their source and their color can be described as black, dark or light. Black boulder opal, though, is almost identical to regular black opal in terms of its colors, light-reflecting qualities and patterns.

Naming rights

Boulder opals were were first discovered in Western Queensland in the 1870s. If you speak to any Australian or opal purist then they will tell you that this is the only true source of boulder opal. However, some people consider the term boulder opal to refer to a cutting style that incorporates part of the host rock into a gemstone. Online you will find stones from mines around the world, including Honduras and Ethiopia, all claiming to be boulder opals. At JupiterGem all of our black boulder opals come from the original source, Australia, as we believe that these stones are of far superior quality.

A history going back millennia

Boulder opal displaying a vibrant “Play of Color” phenomena

Of course, opals were not a 19th century discovery for Australia’s Aboriginal people. The magnificent multi-colored stone had been a part of their lore for thousands of years. There are numerous Dreamtime stories about the origin of opals, many to do with rainbows. One tale relates how the creator decided to visit the earthly realm to bring a message of peace and traveled the land on a vibrantly colored rainbow. Whenever the creator’s feet touched the ground the stones underfoot would take on those brilliant colors, thereby becoming opals.

The takeaway

To go back to the very beginning, let’s end with the answer to the question of why you would choose an Australian boulder opal over a traditional opal. Well, the answer is simple: a black boulder opal will give you the same spectacular look as a regular black opal, but its stone backing means that it has extra strength and hardness, making it ideal for use in jewelry. At JupiterGem we have a wide selection of Australian black boulder opals in stock and an incredible in-house design team waiting to create the mesmerizing opal jewelry of your dreams. So, get in touch and let us add a bit of fiery rainbow splendor to your life! (graduated gemologist, Chantelle Lobo) (graduated gemologist, Chantelle Lobo)

graduated gemologist

Growing up in a country like India, bursting with color, culture and creativity, Chantelle's curiosity drew her towards the fascinating world of gemstones and jewelry. Trained with the best at the Gemological Institute of America and the SSEF, Switzerland, her knowledge encompasses advanced methods of gemstone identification, diamond grading and the manufacture and sales as a jewelry professional. Her adventures have taken her to source Spinels on the busy streets in Myanmar to exceptional Sapphires in Srilanka, a selection of gems from Madagascar and even rare Jades in China. With over 7 years of experience in the jewelry industry, her strong foundation in this niche field allows her to make key observations on the value or quality of gemstones and jewelry. She now continues to fuel her deep-rooted interest for these special stones by seeking out precious one-of-a-kind gems around the world. Linkedin: