You know about opals, but did you know they come in several colours? Black opal is a type of opal known for its dark to black base colour or body tone, extending from dark grey or green to black. In essence, black opal describes any opal with dark body tones. Black opal is often the most highly valued type because the dark base colour allows the gemstone's 'play of colour' to be most bright and sparkling.
The variation between dark and bright makes black opal one of the most prized gemstones, resulting in high price points and a global reputation for quality.
Is black opal rare? And what makes black opal unique compared to other types of opal?
What is Black Opal?
Opal is a colourful class of gemstones ranging from white to orange to black. Black opal shares the same chemical composition and characteristics as all opals. The most valuable opals showcase a feature only seen in opal gemstones - an optical phenomenon called a 'play of colour.'
Almost all black opal is sourced from Australia, though small amounts can be found in other locations. Such a crucial part of Australian culture, opal was officially named the state gemstone of New South Wales's in 2008.
Black opal contains trace elements of common opal left in place on the back of the gemstone to contrast against the play of colour. Black opal's signature colours come from the light diffracted from stacked hydrated silica spheres within the stone. Black opal is hydrated silica-containing from 6% to 21% water.
Rarity
Black opal's stunning colour patterns and combinations make it one of the most highly valued types of opal. Black opal exists bountifully in the gemstone market. Still, high-quality black opal is rare because of the stone's vivid contrast between the dark body tone and rainbow flashes that shine so radiantly across the gemstone. Almost all rare black opal gemstones come from Lightning Ridge in New South Wales.
Black Opal Formation and History
How is black opal formed? Black opal began developing in the Cretaceous period, between 65 and 145 million years ago, with the interior of Australia containing a giant inland sea. The water receded and refilled slowly over millions of years, creating sandy deposits fortified in silica along the shoreline.
Soluble silica grew in cracks and crevices over millions of years, allowing the water to flow into the ground and crystallise into opal veins. Alongside these opal veins, ancient animal carcasses fossilised into opal. These unique conditions have resulted in so much opal being found in Australia.
It certainly creates a sense of wonder about how many undiscovered opal veins and fossilised opal specimens are yet to be found.
Lightning Ridge is considered the home of black opal. Nestled among high ridges and covered with scrub and pebbles, it is here that nature hid of earth's rarest gems, the black opal. Unlike other gemstones, no two opals are the same.
Black opal was first found in Egypt in 1899, with Jack Murray sinking the first hole at the Nobby two years later in 1901 at Jundah, Queensland. Until that time, incredible patterns in opal on such a beautiful black back had never before been seen. Lightning Ridge's supply of black opals dramatically altered how gem merchants assessed opals. Black opal is commonly found as a bar of various colours in a dark body. In addition, there are also semi-black and black crystal opals. Lightning Ridge in New South Wales is known as the worldwide home for black opal and is regarded as producing the best and most reliable source of black opal.
Black Opal Mining in Australia
Black opal is getting harder to find. While fuel prices and lease fees make it very expensive to mine, the scarcity of black opal and associated increases in value make it an incredibly alluring proposition. It is now uncommon to find good quality red fire black opal. The bulk of opal mined at Lightning Ridge is now seam opal, formed in bands similar to Coober Pedy opals. Black opals developed as nuggets are now very rare to come across. The colour base of black opals is even different to years ago - the most common natural base colour is now more of a grey-black colour than dark black. Miners find much more semi-black opal.
Black Opal Properties and Symbolism
Why is it called black opal? As we know from a previous blog post, the name 'opal' derives from the Sanskrit term, 'upala' meaning 'precious stone'. In Rome centuries later, it took on the phrase 'Opallios.' Obviously, 'black' describes the dark body tone.
Opals are porous, said to give them absorbing healing properties. In crystal healing, opals are known as having excellent absorbers of negative energies, thoughts, and influences. They are also said to offer wearers protective properties, giving them strength and perception to choose justice and good purposes.
Did you know that the October birthstone is opal? While opals have at one point garnered an unfair reputation for being bad luck, they have risen to glory by way of striking jewellery designs. Aiding this popularity is their featuring in books and movies.
Black Opal Uses
Black opal's vibrant patterns and colours make it a prime candidate for jewellery designs. Still, there's more to benefit from than stellar style.
Featuring Black Opal in Jewelry
Black opals beautifully accentuate jewellery designs, whether as accent stones, raw gemstones, or in the spotlight of engagement ring centre stones. There are several ways to wear opal jewellery; the first is to buy loose black opal stones and cut them into custom jewellery designs. This method gives you the most control over the appearance and quality of your opal jewellery.
It is important to note that opal is a relatively soft gemstone. Therefore, it is recommended to have the stone is set in a protective setting (such as bezel or claw settings) to ensure longevity.
Healing
Crystals and gemstones are fundamental in spiritual healing and enlightenment, but black opals offer benefits all their own. Black opal properties are said to have therapeutic and cleansing properties, offering body and soul purification. With work and home life being blurred in recent times, it's good to know that black opal is said to help order and organisation, thought clarity, and communication.
Factors to when buying Black Opal
In this section, we'll share the identifying characteristics of black opal.
Colour, Body Tone, and Play of Colour
What is the rarest opal colour? The answer? is black opal! But is black opal really black? Yes, and no. Black opal colours range from black to dark grey, though a dark body tone is found in all black opal. Indeed, that's why black opal is often called 'dark opal.' Trace elements of carbon and iron oxide infuse into the gemstone to make the dark body tone, contrasting the flashes of light which refract exude a full-colour spectrum. The highest quality black opals contain an extensive range of neon colours that collectively create an incredible colour play.
Play of colour describes the interaction of light that occurs solely in opals. Light enters the opal, interacts with the layered silica spheres, and reflects a vibrant flash of colours. What can be seen from this optical interaction is a rainbow display called a play of colour. Black opal often showcases bright blue, green, yellow, orange, and fiery red play of colour variations.
Clarity
Black opals display clarity that ranges from opaque to translucent. The striking appearance of black opals is almost always identified by the occurrence of inclusions. Inclusions are traces of minerals and impurities that create unique colours, patterns, or cloudiness in a gemstone. Some inclusions are undesirable with transparent precious gems like diamonds and emeralds, thus lowering the value. In contrast, they are welcome in opals, such as common opal (potch) in black opal. Typically, black opal should showcase a waxy, shiny lustre without looking synthetic or plastic-like. Nonetheless, the value is diminished when a black opal crazes due to the naturally hydrated stone drying out. The result is crazing and fissures that ruin the stone.
Cut
Cutting and polishing black opal must consider the original rough specimen. For instance, gem cutters and lapidaries often cut the stone to display its most attractive patterns and colour play qualities. The cut most suited to black opal is an oval-shaped style called cabochon. This style doesn't cut any hard lines into the stone; instead, it smoothes the gemstone to illuminate its unique characteristics.
A crucial feature of a good opal cut is the shape of the dome, which can either enhance or diminish the gemstone's colour bars. As such, a low dome will often best display the colour bars, especially if they are thin. Trillion and teardrop shapes are sometimes used for black opals, but they're less commonly seen.
Treatments
High-quality Australian Black Opal will seldom have treatments since the specimens are naturally vivid. This is in contrast to the treatments commonly applied to Ethiopian Black Opal. For example, gems may be soaked in sugar water and sulfuric acid and slowly heated to darken the stone's body tone. In another treatment, the opal is smoked, allowing carbon to penetrate the stone and enhance its colour to be more impressive. In yet another, opals are coated to enhance the colour, introducing polymers and other resins that may alter the gem. While these methods aren't necessarily to the detriment of the stone, it is wise to be wary.
Synthetic Black Opal
Identifying black opal is generally straightforward because you can tell by the stone's dark body tone. That said, it is wise to be mindful of synthetic black opal. These lab-created synthetics can only be detected in a lab with the proper equipment. Synthetic black opal is often overly colourful, with unnatural patterns in a perfect arrangement. Nature makes such gorgeous black opal, with flaws and inclusions that make each gem unique.
Black Opal Origins
Black opal is almost solely sourced from various deposits in New South Wales, Australia. Lightning Ridge is the most significant gemstone source and the largest global supplier of black opal. Ethiopia is another source of black opal - as we learnt above, Ethiopian black opal is typically smoked to enhance the stone's body tone.
Value
Black opals are precious, thanks to their dark body tone and distinctive light effect. The values vary, with the most expensive black opal fetching up to USD 10,000 per carat. What makes it so expensive? It comes down to the remarkable play of colour against a dark body tone. When you look at other types of opal, for instance, crystal or fire opal, you don't see the big contrast of colour and darkness seen in black opals. While these types are indeed lovely all their own, they are not seen in as rare colours and patterns as black opal.
It is possible to find affordable black opals. They are also stunning jewels, even if they don't fall in the elite class of the finest black opals.
Can a black opal be worth more than a diamond? Generally, opals are not as expensive as diamonds; however, the value of a fine-quality rare black opal can surpass even the most brilliant diamond. Once you choose your black opal, you'll want to follow best practices for preserving its quality. Please read our blog on jewellery care to learn more.