Types of Opals
Australia mines 97% of the world's different types of Opals. These include the stunning Black Opals, Boulder Opals, White Opals, Crystal Opals, and Opal Doublets and Triplets. These are made into beautiful varieties of opal rings, opal earrings, opal pendants and necklaces. The other 3% come from Mexico, Brazil, Ethiopia and Hungary but are not the same quality that Australian Opals world renowned for.
The Opal fields of Australia were originally an inland sea. Sea animals were separated, marooned, and Opalised as the aeons passed and the waters retreated. The land eventually dried out entirely and is now arid desert land. Groundwater containing silica solution evaporated over time (with some artesian springs still active deep "underground"). They left behind the phenomena known as 'Opal' in a select places.
Australian Black Opal from Lightning Ridge N.S.W. is the most famous form of Opal in Australia. Hand Cut in Sydney N.S.W. loose Black Opals with Gem colour and a "named" pattern are 5000x rarer than diamond. Watch
Black Opal is formed as water runs down through the earth picking up silica from sandstone. This silica-rich solution is then carried into cracks and voids, caused by natural faults or decomposing fossils. As the water evaporates, it leaves behind a silica deposit. The deposit eventually hardens to form common Opal, and in rare circumstances it forms precious Opal.
The most valuable and popular of all Opals is Black Opal. Black Opal accounts for around 5% and is found at Lightning Ridge in Northern NSW. It is called Black Opal because it has a black base caused by black or grey iron oxide impurities in the Opal.
The colour bar or the 'play of colour' of Black Opal comes in all the colours of a rainbow with red being the rarest and most expensive. A Black Opal is Crystal Opal with iron oxide in the back. It can be grey through to very black. This black potch or common Opal has no value unless we find a colour bar on top of it.
The "Variety" of an Opal is determined by where the Opal Body Tone is located within the Body Tone Chart, which is a chart that the Opal industry recognises as the definition of the "black-base-tone" in a Black Opal. An Opal with a body tone of N1-N4 is defined as "Black Opal". Opals mined in the "Mintabie" fields in South Australia have been known to produce excellent quality Black Opal however are more famous for "Dark Opal" or "semi-Black" or "Grey" Opal, terms used to describe Opals with body tones lighter than N4.
Simply looking at the face of an Opal can tell you if it's a black Opal or not. All colours are disregarded, and an assessment of the total body tone (blackness level) is made. When compared to the scale of blackness illustrated below, stones with values ranging from N1 to N4 are termed Black Opals, garnering the added value associated with this type of Opal.
Natural Opal has not been altered or improved in any manner other than cutting and polishing. Natural Opal comes in three varieties. The "Type" of Opal is determined by determining whether the Opal is "Solid" hydrated Silica or is dispersed with an ironstone host.
A variety of tools are needed to mine the Opals, some more complex or more effective than others.
There has been a rapid increase in the use of mining machines since the 1970s. To expedite Opal mining and substantially enhance output, tunnelling equipment with spinning cutting heads and compact subterranean front-end loaders (boggers) have been introduced.
Miners quickly recognised the advantages of technology, such as drilling test shafts to determine their possibilities before starting real excavation, utilising jackhammers instead of pickaxes, blasting with dynamite, or bringing in bulldozers. Bulldozers are used to remove the overburden and reveal the shallow level. Spotters trail behind, looking for indications of Opal, and any seams discovered are handpicked.
Genuine Natural Australian Black Opal consists of a hydrated amorphous form of concretions of SiO2·nH2O silica consisting of spheres of silicon dioxide molecules arranged in regular, closely packed planes. Black Opal can only be found at Lightning Ridge in N.S.W. Australia. Black Opal is a diminishing resource with anecdotal evidence suggesting increases in value of up to 15% per annum. Australian Opal Cutters Black Opal is Guaranteed to be free of dyes and artificial colour.
Rarity & Value
Valuing Opal is extremely complex! Forget the “4 C’s” Opal requires the detailed examination of over 13 characteristics to assess value:
Variety, Body Tone, Brightness, Transparency, Colour, Hue, Outline or Shape, Profile or Cut, Patterns, Display (Directional or Multidirectional), Distribution of colour (%), Inclusions/Clarity and Carat Weight.
Opal is an extremely precious gem. Black Opal is possibly 130 times rarer than diamond! For every 130 million carats of diamond produced only 1 million carats (or 200 kg) of Opal is mined. And from this rough the loss factor in cutting can be as high as 95 (in black Opal).
Opal is a diminishing resource and there is anecdotal evidence that suggests an increase of up to 25 % per annum in boulder Opal prices and 15 per annum increases in white, crystal and black Opal. The value of an Opal purchase is established when you purchase it as, compared to diamond, ALL Opals are sold for much less than their true worth.
The Boulder Opal is arguably one of the rarest and most valuable forms of Opal found in Australia and makes up less than 5% of all Opal mined. It is very sparsely distributed through Southwest Queensland. It is predicted that Boulder Opal is going to run out in the next 10 years because of the difficulty clearing Native Title and EPA requirements of rehabilitation. Native Title is the process of gaining agreement from the local Aboriginal tribes before mining takes place. This is an extremely difficult and time-consuming process.
Boulder Opal is formed in the cracks and crevices of the ironstone Boulders in a gel form possibly as recently as hundreds of years ago, and with the passing of centuries this jelly Opal turned solid and as you can see, we are left with some beautiful Boulder Opal specimens. Boulder Opal occurs as a filling between the concentric layers or in random crevices in the ironstone. The cutting process is extremely difficult as the cutter must navigate the “hills and valleys” of the Boulder Opal surface. What we are left with is an incredibly unique and individual gemstone. Watch
Boulder Opal is found in the barren, dry, inhospitable region in central Queensland. Found in the "shincracker" layer (resilient Boulder Opal Ironstone). A "spotter" will fly through the desert on a dirt-bike at up to 80kmn per hour looking for "show" (Boulder Opal Ironstone that is visible above the surface). A peg is placed in the ground and then a swimming-pool size hole is excavated. The Opal colour fills microscopic cracks and crevices in a process that is still regarded as a “miraculous” process. To reveal the colour the Ironstone has to be hand-carved by a master gem cutter, a process that is both difficult and time consuming.
Arguably the rarest of all Opal gems Boulder Opal is a diminishing resource (which means it is genuinely running out). Each Opal is unique, each Australian Opal Cutters Boulder Opal gemstone is hand-carved from 'veins' of Opal colour that ebb and flow through the heart of the ironstone. A Boulder Opal ring is a genuinely unique, individual and collectible piece of bespoke Jewelry so it is very difficult to describe. This is one of the benefits of owning a Boulder Opal, there is only one of each! They are genuinely on-of-a-kind pieces due to the absolutely organic and natural way the colour flows through the cracks and crevasses as well as the incredible and amazing colour play.
Boulder Opals are exceptional as they are so incredibly unique. In each Boulder Opal there is a world of discovery as the colour and shapes ebb and flow in absolutely unique patterns and colours in every gem. This makes wearing a Boulder Opal ring a very precious and individual experience, and one that will always receive endless compliments and comments of admiration from friends and colleagues.
There is no solid scientific explanation as to how the hydrated silica forms in the ground, however, there is a general consensus as to how the actual gemstone is created. As it is permeating into these cracks and crevices, there is occasionally a hole that is formed by a gap, fissure or crack being opened up within the layers of the Boulder Opal (or, with crystal opal foreign element such as a marine dinosaur such as squid bone, small pieces of wood, or a shell).
Although carbonated materials usually fill these holes, occasionally hydrated silica of the Opal has filled the hole and solidified. This process is a rare occurrence, and as a result, there is limited potential for a miner to find Opalised material filling what would otherwise be ‘cracks’ or ‘crevasses’ in the Boulder Opal.
Genuine Natural Australian Boulder Opal consists of a hydrated amorphous form of concretions of SiO2·nH2O silica consisting of spheres of silicon dioxide molecules arranged in regular, closely packed planes filling the cracks and crevices of Boulder Opal ironstone found remotely in Queensland Australia. Boulder Opal is a diminishing resource with anecdotal evidence suggesting increases in value of up to 15% per annum. Guaranteed free of dyes and artificial colour.
Rarity and Value
Boulder Opal is incredibly rare due to multiple factors, including the limited amount that can be mined, and the high loss factor that is experienced when cutting (only yielding 5% of what is brought in), subsequently resulting in a diminished market. As a gem, Boulder Opal is significantly increasing in value, as the amount currently circulating is only finite, and therefore is suggested to run out in the next 5-10 years.
In the 1980’s there were approximately 200 miners working the Boulder Opal fields in Queensland. This figure has dropped dramatically as there is now a mere handful (estimated to be only 20 miners in 2018). There are two main factors for this change. The first is a natural resource mining boom that Australia has experienced in the exploration of Oil, Gas and other ores. Opal miners earn ‘big money’ and are leaving the fields for this reason.
Secondly On average, Opals with a darker tone are considered to be more valuable in comparison to lighter variants. This is mainly due to the fact that a darker stone will display the colours on its surface with more intensity, making them more vibrant than a white stone that may have the same hues.
Opal is Australia’s National gemstone and White Opal is the most famous form of Australian Opal and most seen in a ring, pendant or earrings. White opal is mined in South Australia and is easily distinguishable from other types of opal due to its lighter colouration. The white tone is a result of magnesium oxide in the silica and is often described as a ‘pale white’ or a ‘milky’ complexion. This type of opal is more common in comparison to others, however that doesn’t stop it from being truly beautiful and valuable. Watch
Coober Pedy was discovered in 1915. This is where most of the 'white' or 'milky' and crystal opals (together known as 'light opal') are mined. Coober Pedy is the main producer of white precious opal, which is predominantly seen in stores overseas, particularly in the USA. Today, the opal fields encompass an area of approximately 45 kilometres. The opal level is formed of soft pinkish clay mixed with soft bleached sandstone.
The name “Coober Pedy” is an Aboriginal word that translates “man in a hole” and with temperatures around 40 degrees Celsius or 100 degrees Fahrenheit all year the cool underground mines have become popular as living quarters, and now most of the locals live underground!
The name opal was probably derived from a Sanskrit description of white Opal "upala", meaning "valuable stone" or from the Greek word "opallus" which means to see a change in color. The most likely location for the original Roman or Indian connection to Opal were the small quantities mined for centuries in Hungary.
Later, the Latin term "opalus," which means valuable stone, was coined. A so-called "opalus," or "stone composed of various pieces," existed in Roman antiquity. Pliny the Elder, a prominent Roman author, described opal as a gemstone that "combines the greatest conceivable attributes of the most beautiful of gemstones”. Such as almandine's delicate glitter, amethyst's dazzling purple, topaz's golden yellow, and sapphire's deep blue, "so that all colours shine and glitter together in a lovely combination."
These “white” Opals were considered to be incredibly valuable and powerful by the ancient Romans.
Australian White opal was discovered at Coober Pedy in 1915; most of the opals classified as ‘white’, ‘mily’, or ‘crystal’ are mined at this location, even today. As a result of this, Coober Pedy is the main producer of this precious stone, and therefore exports of such stones often originate from this location.
Genuine Natural Australian White Opal consists of a hydrated amorphous form of concretions of SiO2·nH2O silica consisting of spheres of silicon dioxide molecules arranged in regular, closely packed planes filling the pockets and cavities left behind by dissolved mineral deposits, fossils or plant material in Coober Pedy in South Australia. White Opal is a diminishing resource with anecdotal evidence suggesting increases in value of up to 7% per annum. Australian Opal Cutters White Opals are Guaranteed free of dyes and artificial colour.
Rarity and Value
When compared to other opals, white opal is the least valuable. This is because they are a common form of opal to be found, in addition to their light colouring, as the darkness within an opals stone leads to the more vibrant colour (as can be seen in boulder opals and black opals).
Fire Opals are Opals from Mexico or Brazil and are prized for their beautiful orange, yellow, and red “fire” and hues. The most valuable specimens have a vibrant and fiery red or orange hue and uniform colour. Milkiness is sometimes seen if the Opal dries out, which can, unfortunately, lead to cracking for this type of Opal.
At the same time, fire Opals may often lack the play of colour seen so prominently in Black Opal, shoppers prize “fire Opals” for their beautiful hues and generally lower price. However, these are less popular for an engagement ring as they are prone to cracking and therefore not as desirable.
Opals have a unique grading system, with special terminology that is used during appraisals. Such terminology is essential to keep in mind when searching for engagement rings, as it can allow for a deeper understanding of your jewelry overall. When shopping online, keep in mind these qualities:
- The best quality opal has colours that are uniformly spread around the stone.
- The harlequin design, which uses a variety of colours, is the most valuable. It’s made up of a patchwork of diamond-shaped flashes that run the length of the stone.
- Pinfire, a pattern of vivid, colourful spots, is frequently seen in White Opals.
- Furthermore, any red-based play-of-colour pattern is highly prized.
Fossilised Opal, translucent, transparent Crystal Opal is found in South Australia and NSW and is incredibly rare and beautiful.
Crystal opal is pure hydrated silica, or pure Opal. It does not contain any oxides (the material that turns an Opal white or Black); Crystal Opal is translucent so you can see straight through it when you hold it up to a bright light.
Crystal Opal often exhibits many of the most sought after (most valuable) traits when valuing an opal. The colour is usually multi-directional (meaning, colour can be seen from many different angles), with large blocks of colour that can be vibrant enough to see in very low light.
All Opals have a “crystalline’ structure, so the name ‘Crystal” is a reference to the translucent appearance as opposed to the structure being different to any other form of Opal (as the molecular structure and chemical composition is basically the same). Other forms of Opal (such as Boulder, Black and White Opal) can all display the trait of crystalline translucency are not called ‘crystal’, with Boulder Opal this is because they have the ironstone base. A Black Opal that is translucent may be known as a “Black Crystal”.
The translucence of these gems often increases the vibrancy of colours, as light can easily pass through accentuating the rainbow diffraction effect. The nature and shape of the stone will also have a great impact on the colour exhibited, crystal opals are therefore often ‘carved’ to maximise the amount of Opal that can be extracted from the rough Opal material and maximise the display through volume. Traditionally either a standard ‘oval’ shape, ‘round’ or a ‘teardrop’ shape was the “standard” from the 1890’2 through to the 1960’s. “Carving” was really adventurous but far more common today.
While crystal Opals can occur in very limited quantities in all of the Opal fields (even boulder Opal can show translucent crystal Opal forming in the seams, cracks and crevices. These opals are usually found and mined in South Australia in a field called Andamooka.
Genuine Natural Australian Crystal Opal occurs in limited quantity in all of the Australian Opal fields (Andamooka, Lightning Ridge in NSW, Coober Pedy in South Australia and the Queensland Boulder Opal Fields). A hydrated amorphous form of silica SiO2·nH2O consisting of spheres of silicon dioxide molecules arranged in regular, closely packed planes. The Opal is pure hydrated silica SiO2·nH2O “free” from oxides (Magnezium) so it has a clear translucency.
Precious Crystal Opal has a varied interplay of interior colours, and it has an interior structure despite being a mineraloid. At microscopic sizes, precious opal is made up of 150 to 300 nm diameter silica spheres arranged in a hexagonal or cubic close-packed lattice. J. V. Sanders demonstrated in the mid-1960s that these ordered silica spheres generate the interior colours by forcing light flowing through the opal's microstructure to interfere and diffraction.
Dinosaurs and other ancient creatures once inhabited a great Inland Sea in the heart of the Australian Outback (The Artesian Basin, where Lightning Ridge is now located). These dinosaur plants and bones have been used to create many of the spectacular Crystal Opals. They are Australian National Treasures, scientifically significant, and among the world's most beautiful and precious fossils.
Crystal Opal fossils are formed in rock cavities where a piece of a living creature – such as a bone, shell, or pinecone – was buried in the sand or clay before it converted to stone. Here, the opal can act as a fossil reproduction of the buried object.
“The remnants or evidence of an old animal or plant preserved in rock” is what a fossil is. Opalised fossils are formed in the same way as other fossils, but they are preserved in silica. Fossils can also be found in minerals like agate, pyrite, and limestone.
Internal details are only kept in a few circumstances. The organic molecules can be replaced by silica if it penetrates the organic substance before it decomposes. This retains the tiny intricacies of the bone or plant's internal structures. This interior anatomy is apparent from the outside when the silica is transparent: the fossil is ‘see-through.'
These are the most precious and genuinely stunning of all crystal Opals! They reveal fresh and intriguing knowledge about Australia's history and the many flora, animals, and ecosystems that can be found on the continent.
Lightning Ridge and a few boulder opal fields are the only areas in Australia where you may find opalized fossils of land-living and freshwater plants and animals. The fossils of saltwater or marine creatures found in other Australian opal fields give further information about Australia's history and the old Eromanga Sea.
The only area on Earth that generates opalized bones of land-living creatures, including dinosaurs, is Lightning Ridge. The creation of fossils and opals are inextricably intertwined. The study of opalized fossils might lead to new insights into opal creation and aid in opal research and prospecting.
Rarity and Value
Quality crystal opals often result in a high value. This is because the overall clarity of the colours is a direct result of the shape, size, and type of stone, and is therefore unable to be replicated in other pieces, therefore giving the crystal opal a higher value than a ‘standard’ opaque opal.
Opal can shows a broad range of “diaphaneity” (transparency) that ranges from transparent to opaque. Natural precious opal (which is transparent to semi-transparent) is defined as “crystal opal”. Crystal opal can have either a black, dark or light body tone. In this context, the term ‘crystal’ refers to the appearance of the opal and not its crystalline structure. Crystal opals will often “face-up” more brilliantly against a black background (which enhances the brilliance of these opals’ play-of-colour). The same crystal opal shown against a reflective (or white) background will often “subdue” the opal’s “play-of-colour”. When purchasing an Opal on the internet it is important to see the Opal displayed against a black background and a white background as there can be a dramatic difference in the “appearance” when placed against the different backgrounds.
The value of an Opal is technically not affected by these display differences unless an unscrupulous seller was to judge the characteristics of the Opal when displayed against a black background and studio lights (as all appraisals should be conducted in ‘neutral’ conditions without enhancing elements.
Australian Opal is so rare and valuable we will often cut larger Opals into ‘slices’ to allow us to make rings, pendants and earrings that are affordable.
Not everyone can afford tens of thousands of dollars for a pendant or ring. By taking a ‘slice’ (or piece) of an Opal and laying this against a background of Boulder Opal (or Black Opal) “potch” (Opal without colour) we are able to provide a completely natural piece of Opal in all of its splendour and beauty and make it affordable!
We make and distribute two types of enhanced opals, doublets and triplets. Not only do these types of opals look amazing, but they’re approximately around 1/30th the price of a black opal, making them affordable alternatives to more expensive subcategories of opal. This is because they are composed of different layers of opal and stone, rather than a ‘solid’ piece. Usually there is a thin layer of crystal opal coupled with a layer of potch (black common opal) or ironstone on the back, which acts to bring out the colour of the opal.
As a whole, doublets and triplets exhibit incredibly vibrant tones, due to their dark backing that enhances and allows the natural beauty to leap out of the heart of the gemstone.
In order to ensure quality, we focus on the quality of materials utilised to create such a backing. We use Black Opal “potch” (which in itself can be very difficult to find). This is the material that we excavate in the mines at Lightning Ridge and cut to search for the elusive gem colour. When we find black Opal ‘nobbies’ (rocks) without colour we keep them and slice them up to use as a backing for a doublet. The Boulder Opal used to back doublets is also from the ‘darker’ end of the boulder Opal “N-Scale” and generally the harder (less porous) form of Boulder Opal. This makes an amazing base for a slice of Black, White or Crystal Opal and is tough and resilient and lasts.
Because we provide quality composition of both doublets and triplets, we can guarantee our products for life against delamination. This is the process where (in inferior products) the layers of a Doublet or Triplet can be affected when they come into contact with water. Water can affect the glue, dissolving the layers and causing the Opal to turn “white”. In these situations, it is not actually the Opal turning white but the glue being affected by water and dissolving!
By using Boulder or Black Opal as the “base”, and the same silica-based glues used on the aerospace programs Australian Opal Cutters has created Opal Doublets and Triplets that are guaranteed for life against delamination.
Opal miners have always struggled to get prices for opal that not only correlates to the stone’s true rarity but is affordable. Throughout history large Opals (known as “Kingies”) have been incredibly valuable, but also difficult to sell.
A common and simple solution that developed was to take these beautiful, priceless gemstones, and cut them into finer ‘layers’. These layers are then placed on sections of solid opal in order to contrast (and subsequently intensify) the colour. This meant that consumers could acquire adequately priced jewelry, and miners could still pay for their expensive equipment. Some might say that it is tragic to cut up the larger gems, but the economics have demanded that Opal miners do this in order to survive.
We offer our warranty and service guarantee against delaminating, and we have never had a customer return a doublet or a triplet; we currently utilise a NASA-developed silica-based bonding process which allows for durability and strength. Once all of the layers are bonded together with a silica-based process, the coefficient-of-expansion remains constant allowing the layers to expand and contract at the same rate. This coefficient means that the layers do not ‘work apart’ over time!
Genuine Natural Australian Gem Doublet Opal is a hydrated amorphous form of silica SiO2·nH2O consisting of spheres of silicon dioxide molecules organised in regular, closely packed planes backed by Boulder Opal ironstone (found in remote areas in Queensland Australia). Guaranteed free of dyes and artificial colour.
Rarity and Value
Doublets and triplets are very popular due to their durability and relatively inexpensive nature. As an example, a simple triplet pendant might be sold at $1000, whereas a white opal piece with the same colour and pattern might be $4000, a crystal opal $8000, or a boulder opal with $16,000, or a Black Opal with exactly the same colour and pattern as the Triplet would be $32,000. There really is that much of a difference between a thin ‘layer’ and a solid Opal gem (even if that solid Opal gem is only a few millimetres thick)
We make and distribute triplets. Not only do these types of opals look amazing, but they’re approximately around 1/40th the price of a black opal, making them affordable alternatives to more expensive subcategories of opal. This is because they are composed of different layers of opal and stone, rather than a ‘solid’ piece. Usually there is a thin layer of crystal opal coupled with a layer of potch (black common opal) or ironstone on the back, which acts to bring out the colour of the opal and capped with a Quartz crystal cap (for strength and color magnification).
Triplets are similar to a doublet, with the main difference being the quartz cap on the surface of the stone that acts to magnify and enhance the colour of the opal. This results in a higher refractive index within the jewelry, usually aiding in amplifying and magnifying the various colours and patterns seen within. The addition of this ‘magnifying lens’ creates what we know as a ‘triplet’. The lens is also extremely durable and resilient, able to withstand (literally) being hit with a hammer! This feature is what makes Triplets a very popular choice for everyday wear.
An Australian Opal Cutters triplet is made from 100% natural materials. It contains no dyes, treatments or plastics. As all opals are different (no two are alike) it is extremely difficult to find earring pairs. Triplet earrings however take solid white and crystal Opals and slice them into fine layers. A thin slice of Opal is then carefully placed on a layer of natural Australian black Opal “potch” (Opal without colour).
As a whole, triplets exhibit incredibly vibrant tones possibly the ‘brightest’ displays for any “type” of Opal. This is due to their dark backing that enhances and allows the natural beauty to leap out of the heart of the gemstone and the magnification from the quartz crystal cap.
In order to ensure quality, we focus on the quality of materials utilised to create such a backing. We use Black Opal “potch” (which in itself can be very difficult to find). This is the material that we excavate in the mines at Lightning Ridge and cut to search for the elusive gem colour. When we find black Opal ‘nobbies’ (rocks) without colour we keep them and slice them up to use as a backing for a Triplet. The Boulder Opal used to back Triplets is also from the ‘darker’ end of the boulder Opal “N-Scale” and generally the harder (less porous) form of Boulder Opal. This makes an amazing base for a slice of Black, White or Crystal Opal and is tough and resilient and lasts.
By using Boulder or Black Opal as the “base”, and the same silica-based glues used on the aerospace programs Australian Opal Cutters has manufactured Opal Triplets that are guaranteed for life against delamination.
Opal miners have always struggled to get prices for opal that not only correlates to the stone’s true rarity but is affordable. Throughout history large Opals (known as “Kingies”) have been incredibly valuable, but also difficult to sell. A common and simple solution that developed was to take these beautiful, priceless gemstones, and cut them into finer ‘layers’.
These layers are then placed on sections of solid opal in order to contrast (and subsequently intensify) the colour. This meant that consumers could acquire adequately priced jewelry, and miners could still pay for their expensive equipment. Some might say that it is tragic to cut up the larger gems, but the economics have demanded that Opal miners do this in order to survive.