The Complete Guide to Australian Opals: Types, Value & How to Choose

Australia produces roughly 95% of the world's precious opal, making Australian opals the global benchmark for quality, colour, and variety. At NJewellery, we source our opals directly from Australian mines and set them by hand in gold and silver designs created in our workshop. This guide will help you understand the different types of Australian opal, how to judge quality, and what to look for when choosing an opal piece.

What Makes Opal Special?

Opal is unlike any other gemstone. Its defining characteristic — play-of-colour — is caused by the diffraction of light through a microstructure of tiny silica spheres arranged in a grid pattern. As light passes through these spheres, it splits into spectral colours that shift and dance as you move the stone. No two opals produce exactly the same pattern, making every opal genuinely one of a kind.

Precious opal (opal that displays play-of-colour) is found on every continent, but the most vivid, stable, and sought-after stones come from the opal fields of outback Australia — Lightning Ridge, Coober Pedy, Winton, and Andamooka among them.

Types of Australian Opal

Black Opal

Black opal is the most valuable and prized type of Australian opal. Found almost exclusively at Lightning Ridge in New South Wales, black opal has a dark body tone (ranging from dark grey to jet black) that acts as a dramatic backdrop for its play-of-colour. Against this dark base, the spectral colours appear vivid and electric — reds, greens, blues, and purples can blaze from the stone with extraordinary intensity.

Top-quality black opal with strong red play-of-colour (known as "red-on-black") is among the most expensive gemstones in the world, with exceptional stones fetching tens of thousands of dollars per carat.

Boulder Opal

Boulder opal forms as thin veins and patches within ironstone boulders, primarily in western Queensland. The opal is cut with its ironstone backing still attached, which provides structural support and creates a natural dark background that enhances the colour play — similar to black opal but with a more organic, earthy character.

Boulder opal is prized for its dramatic patterns and the way the opal seam follows the contours of the host rock. Each stone tells a geological story. Our Boulder Opal Gold and Silver Ring and Boulder Opal Ring with Diamond showcase the rugged beauty of Queensland boulder opal.

Crystal Opal

Crystal opal is transparent to semi-transparent, allowing you to see into and sometimes through the stone. When crystal opal has vivid play-of-colour, the effect is mesmerising — like looking into a tiny galaxy of shifting light. Crystal opal can range from completely colourless (water opal) to slightly milky, with the most valuable pieces being those with both high transparency and strong colour play.

We work extensively with crystal opal in our gold ring designs. Our Crystal Opal Ring with Peach Sapphire and Crystal Opal Ring with Diamond pair crystal opals with complementary gemstones that enhance their ethereal quality. Read our detailed article on crystal opal and its unique play-of-colour.

White Opal

White opal (or light opal) has a white or light body tone and is the most common type of precious opal. Coober Pedy in South Australia is the most famous source, though white opal is found at several locations across Australia. While white opal generally commands lower prices than black or boulder opal, fine specimens with bright, broad colour play are still highly desirable. Our Four Petal Gold Pendant with White Opal features a beautiful Coober Pedy stone.

How to Judge Opal Quality

Opal is graded differently from other gemstones. There is no universal grading system like the 4Cs for diamonds, but experienced dealers and gemmologists evaluate opals based on several key factors:

Play-of-colour: This is the single most important factor. Brighter, more vivid colours are more valuable. Red is the rarest and most prized colour in opal, followed by orange, then green, then blue. An opal that displays the full spectrum (known as a "harlequin" pattern in its rarest form) is exceptionally valuable.

Pattern: The arrangement of colour within the stone matters. Broad, rolling flashes of colour (broadflash pattern) are generally more valued than small, scattered pinpoints (pinfire pattern). Other desirable patterns include flagstone, ribbon, and the highly prized harlequin.

Body tone: Darker body tones generally make the play-of-colour appear more vivid. Black opals command the highest prices, followed by dark opals, then semi-dark, then light. Crystal opals are evaluated on a separate scale where transparency and brightness are paramount.

Brightness: How vivid the play-of-colour appears, rated from subdued (1) to brilliant (5). A stone rated 4 or 5 for brightness will display vivid colour even in low light conditions.

Shape and size: Larger opals that maintain high quality are disproportionately rarer and more valuable. A well-shaped cabochon with good dome height displays colour play to best effect.

Solid Opals vs. Doublets and Triplets

When shopping for opal jewellery, it is essential to understand the difference between solid opals, doublets, and triplets:

A solid opal is a single piece of natural opal, cut and polished. This is the most valuable form and the only type we use at NJewellery. Solid opals can be safely cleaned with water and worn daily.

An opal doublet is a thin slice of natural opal glued to a dark backing (usually ironstone, obsidian, or black glass). The dark backing enhances colour play, making a thin slice of opal appear similar to a solid black opal. Doublets are more affordable but must be kept away from water, as prolonged soaking can weaken the adhesive and cause the layers to separate.

An opal triplet adds a third layer — a clear quartz or glass dome on top of the doublet — to protect and magnify the thin opal slice. Triplets are the most affordable option but are the least durable and most sensitive to moisture.

Reputable jewellers always disclose whether a stone is solid, doublet, or triplet. If the price seems too good to be true for a "black opal," it is almost certainly a doublet or triplet.

Caring for Your Opal Jewellery

Australian solid opals contain between 3% and 10% water, which gives them their characteristic play-of-colour but also makes them more sensitive to extreme conditions than most gemstones. Here are the key care guidelines:

Avoid exposing opals to sudden temperature changes, prolonged direct sunlight, or very dry environments (like near heaters or air conditioners). These conditions can cause the stone to lose moisture and develop fine cracks known as "crazing." Store opal jewellery in a soft cloth or pouch — some collectors keep a slightly damp cotton ball in the storage box during very dry seasons.

Clean opals with lukewarm water and a soft cloth. Never use ultrasonic cleaners, steam cleaners, or chemical solutions. Opals rate 5.5 to 6.5 on the Mohs hardness scale, making them softer than many gemstones, so store them separately to avoid scratches.

With sensible care, a quality solid opal will retain its beauty for generations. Many antique opal pieces from the Victorian era still display brilliant play-of-colour today.

Why Choose Australian Opal?

Australian opals are prized worldwide for good reason: the country's unique geological conditions produce opals with more vivid colour play, greater stability, and wider variety than those from any other source. Ethiopian opals, while beautiful, are hydrophane (they absorb water) and can be less stable over time. Mexican fire opals offer striking orange colour but rarely display the play-of-colour that defines precious opal.

When you buy Australian opal jewellery from NJewellery, you are getting stones sourced directly from Australian mines, set by hand in our workshop. Learn more about why Australian handmade jewellery offers something mass-produced pieces simply cannot match.

Explore Our Opal Collection

Browse our full range of Australian opal jewellery and gold rings with opals and gemstones. Every opal we use is a natural, solid Australian stone — no doublets, no triplets, no synthetics. For more on the gemstones we work with, read our articles on the mystique of Australian opals and semi-precious gemstones, or explore our wider opals, diamonds and gemstones collection.

Frequently asked questions

What types of Australian opal are there?

The main types are black opal (from Lightning Ridge, most valuable), boulder opal (from Queensland, opal in ironstone), crystal opal (transparent with play-of-colour), and white opal (from Coober Pedy, light body tone with colour play).

What is the difference between solid opal, doublet, and triplet?

A solid opal is one natural piece. A doublet is a thin opal slice glued to a dark backing. A triplet adds a clear dome on top of a doublet. Solids are most valuable and durable; doublets and triplets must be kept away from water.

How do you care for opal jewellery?

Avoid sudden temperature changes, prolonged sunlight, and very dry environments. Clean with lukewarm water and a soft cloth. Never use ultrasonic or steam cleaners. Store separately in a soft pouch.

Why are Australian opals considered the best?

Australia produces about 95% of the world's precious opal. The unique geological conditions produce opals with more vivid play-of-colour, greater stability, and wider variety than those from any other source.