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What is Opal?
Opal is one of the most captivating gemstones in the world, known for its remarkable play of colour, where flashes of colour shift and move as the stone is viewed from different angles.
This natural phenomenon forms when silica rich solutions slowly solidify within cracks and cavities in rock.
Over time, microscopic silica spheres arrange themselves within the stone, creating the internal structure responsible for the colours seen in precious opal.
Australia produces the majority of the world’s precious opal. The most prized material comes from Lightning Ridge in New South Wales, renowned as The Home of The Black Opal.
Black opal is particularly valued for its naturally dark body tone, which intensifies the contrast and brilliance of colour within the stone.
Body tone scale
The Body Tone Scale measures the lightness or darkness of an opal’s background, ranging from white to black. To use it, place your opal face-up on the chart and slide it along until its tone matches one of the reference samples, helping you accurately determine its body tone grade.
The Body Tone Scale measures the lightness or darkness of an opal’s background, ranging from white to black. To use it, place your opal face-up on the chart and slide it along until its tone matches one of the reference samples, helping you accurately determine its body tone grade.
Brightness scale
The Brightness Scale measures the intensity and vibrancy of an opal’s play of colour, indicating how strongly the colours appear under light. To use the scale, place your opal face-up on the chart and move it along until its brightness most closely matches one of the reference levels. This helps you accurately assess the opal’s overall brilliance and visual impact.
The Brightness Scale measures the intensity and vibrancy of an opal’s play of colour, indicating how strongly the colours appear under light. To use the scale, place your opal face-up on the chart and move it along until its brightness most closely matches one of the reference levels. This helps you accurately assess the opal’s overall brilliance and visual impact.
B5
Vivid
B4
Very Bright
B3
Bright
B2
Moderately Bright
B1
Subdued
Please note:
This Body Tone and Brightness Scale is intended as a general reference only. Any decisions made using this guide are at the user's discretion and no liability is assumed. For most accurate results, laser print this guide on Artboard 350gsm paper stock or similar.
Types of Opal
Black Opal
Black opal has a dark body tone that intensifies the brightness and contrast of colour. The finest examples come from Lightning Ridge.
Dark Opal
Semi black opal has a slightly lighter body tone than black opal but can still display strong colour.
Crystal Opal
Crystal opal is transparent to semi-transparent and allows light to pass through the stone, often enhancing the brightness and depth of colour.
Grey Opal
Grey opal has a medium body tone between black and white opal.
White Opal
White opal has a light body tone and softer colour contrast.
Opal Grades
Opal quality can vary widely and there is no single global grading system. Instead, stones are often described by general quality levels based on brightness, colour, pattern, and overall appearance.
Commercial Grade
Material with lighter colour play or limited pattern. Often used in jewellery or entry level stones.
Jewellery Grade
Opal displaying good colour and brightness suitable for jewellery settings.
High Grade
Stones with strong colour, good pattern, and attractive overall presentation.
Collector Grade
Exceptional stones displaying outstanding brightness, colour range, and pattern. These pieces are often sought after by serious collectors and high end jewellery makers.
Gem Opal vs Lower Grade Opal
The value and quality of opal are influenced by several natural factors:
Brightness
Stronger and more vivid colour play is generally more desirable.
Body Tone
Darker body tones often enhance the contrast and visibility of colour.
Pattern
Distinct and well defined colour patterns are often more valuable.
Colour
Range
Opals displaying multiple colours or strong reds and oranges are typically more sought after.
Each opal is naturally unique, which is part of what makes the gemstone so fascinating.
Rough, Rubbed and Finished Opal
Opal may be seen at different stages before becoming a finished gemstone.
Rough

Rough opal is material in its natural state as it comes from the ground.
Rubbed Opal
A rub is partially shaped opal where the outer material has been removed to expose the colour bar. This helps reveal the potential of the stone before final cutting.
Finished Opal
A finished opal has been fully cut and polished, ready to be set into jewellery or added to a collection.
Nobby Opal vs Seam Opal
Lightning Ridge Opal is commonly found in two main forms; Nobby Opal and Seam Opal.
Nobby Opal forms as rounded or irrecular nodules. These pieces can be unpredictable, however they are highly sought after because a single Nobby can reveal strong colour, unusual patterns, and even more valuable when it produces on black opal.
Seam Opal forms in flatter layers or veins through the host rock. It can be easier to read than Nobby Opals because the colour may be more visible, but as with any opal the final results depend on the individual piece.
Both forms can produce exceptional Lightning Ridge Opal. The skill is reading the indicators, understanding the risks, and having an awareness of your own skill level before deciding if a piece of Opal is for you.
Shop Opals
Sold out
28.7 gram Lightning Ridge dark and black opal rough parcel. Bright greens, blues and purples. A bright little rub in the mix alongside stones with promise and honest gambles. Suitable for beginners or the more experienced person who likes a challenge. "They Don't Have To Be Big In The Ridge." Free shipping within Australia.
Authentic. Rare. Unforgettable.
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29.78x32.43x12.48mm
A 47.65ct rough black opal nobby. Blue, purple and green showing throughout the stone and across the windows. Sand evident around the edges, yield unknown. The opportunity within it is what makes it interesting.
Authentic. Rare. Unforgettable.
new
21x19x7mm
A window into a dark to black Lightning Ridge nobby, blue and green flash cutting through the stone.
Honest rough, sold as seen, for the cutter ready to find out what's underneath.
Authentic. Rare. Unforgettable.
-9%
A dark to blue bar settling through the stone, forming the main body of this knobby.
-10%
28.81ct mixed base rough nobby parcel. Varying body tones, purples, blues and greens. The king stone is a green, blue on black nobby that reads black opal. One bright orange piece with pointer promise. "They Don't Have To Be Big In The Ridge." Amongst other pieces, there is further potential waiting to be uncovered. Free shipping within Australia.
Authentic. Rare. Unforgettable.
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23.34x19.83x6.37mm
13.40ct dark black opal nobby, snipped on three sides. Potential for N2 black potch. N5 dark base. Electric greens, golds and blues showing at B4 to B5 brightness. Flagstone chaff with rolling elements. Torch shows light consistently through the majority of the stone. Minimal waste. For someone with confidence and experience.
Authentic. Rare. Unforgettable.
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35.05x38.19x11.05mm
A 65.55ct black opal nobby from the Corcoran field. Electric blue wrapping the entire exterior, consistent and bright. Natural ironstone matrix. Complete nobby form. A specimen that makes its point without any help.
Authentic. Rare. Unforgettable.
new
31.69x32.12x11.26
A 46.70ct black opal nobby in its natural split form, both halves together. 32.15ct and 14.55ct. Thick bright bars of electric blue and green running from skin to skin. Black opal exactly as nature made it. A collector's specimen that rewards every return visit. In its natural form, it needs nothing.
Authentic. Rare. Unforgettable.
Frequently Asked Questions
Opal Hub Australia specialises in Lightning Ridge opal including Black Opal, Semi Black Opal, Crystal Opal, Grey Opal, and White Opal, along with selected rough opal, rubs, fossils, specimens, and finished stones. All stones are natural solid Australian opal unless clearly identified otherwise.
Black Opal has a naturally dark body tone that intensifies the brightness and contrast of colour within the stone. The finest Black Opal in the world comes from Lightning Ridge, New South Wales, making it the most prized and sought after opal on earth.
Crystal Opal is transparent to semi transparent opal that allows light to pass through the stone, often enhancing the brightness and depth of colour.
Knobby opal forms as rounded or irregular nodules within the surrounding claystone. It can be unpredictable, but may reveal strong colour, unusual patterns, or valuable Black Opal once opened and cut.
Seam opal forms in flatter layers or veins through the host rock. It can sometimes be easier to read when the colour bar is visible, but the final result still depends on thickness, direction, body tone, brightness, and the cutter’s skill level.
Both forms are found at Lightning Ridge and can produce exceptional opal when the material is read correctly.
Doublets and triplets are assembled opal stones made using thin slices of opal combined with backing materials or protective caps. Any doublets or triplets sold by Opal Hub Australia are clearly identified.
No. Opal Hub Australia does not sell synthetic opal.
For a full breakdown of opal types, grades, and what to look for, visit our Opal Guide.
Rough opal is opal in its natural state as it comes from the ground. It may contain colour bars or patterns that require cutting and polishing to reveal the finished gemstone.
A rub is partially shaped opal where the outer material has been removed to expose the colour bar and better assess the potential of the stone before final cutting.
A finished opal has been fully cut and polished, ready for jewellery or collecting.
Yes. Buyers should understand that rough opal always carries uncertainty and cutting results can never be guaranteed.
Yes. Some parcels are better suited to beginner cutters, while others are intended for experienced cutters and industry buyers.
Yes. Educational insight into rough opal, cutting, and reading material is shared through Opal Intelligence.
Yes. Some material is better suited to experienced cutters, lapidaries, or industry buyers who understand the risks and potential of rough opal.
Several factors influence opal value including body tone, brightness, colour play, pattern, size, rarity, and overall presentation.
When assessing an opal, consider how the colour plays across the stone, the brightness under light, the body tone, and the pattern. For rough opal, look for visible colour bars and consider the potential of the stone. If in doubt, Opal Intelligence is a great place to start learning.
