How is Opal Formed? - the Geology of Opal

Geological factors linked with the formation of opal are still being researched and are subjects of active discussion among geologists, miners and opal prospectors.

There are three primary models for the formation of opals and although they are independent of each other, a link may exist among them.

Weathering Model

A majority of the opals recovered from opal fields in Lightening Ridge are found close to the top of many Finch clay facies lenses just underneath the overlying part of Wallangulla Sandstone Member. When these opal fields are geologically mapped, it is seen that the thickest sandstone is found in areas with the largest concentration of opal. The gemstone is rarely found in places where sandstone is scarce.

This data concurs with the view that weathered sandstone is the silica source for opal formation. The finding of opal in upper reaches of Finch clay facies is in accordance with a concept of siliceous solutions (a ground water and silica mix) percolated down from Wallangulla Sandstone Member (the source rock) by impervious barrier of clay fades or opal dirt.

Additional factors for opal formation involve:

• The alteration from alkaline to acidic environment
• Presence of ferric oxide, magnesium oxide or aluminum oxide
• sodium sulphate or sodium chloride being present

Syntectonic Model

This geographical model forwards the view that the opal created from the mineral enriched waters rising to the land surface under substantial pressure through breccia and fault pipes. Tectonic and large scale geological processes forced water hydraulically into faults and fractures. After the water is dissipated into lower pressure areas, opal gets deposited as the veins.

The basic concepts linked with syntectonic model are;

• Development of opal occurred post rock formation where it is available.
• The gemstone was formed comparatively swiftly
• Blows and faults are prerequisites for opal formation in a particular area.

Microbe Model

The claystone containing opal normally contains significant quantities of organic matter which were fossilized thousands of years ago. Many categories of aerobic bacteria along with microbe fossils have been marked with opal samples from Lightning Ridge immediate area.

When the deposition of cretaceous sediments, a luxury of smectite clay and organic matter inside a few sediments offered an ideal ecology for microbe breeding. Enzymes and waste acids excreted by microbes resulted in weathering of feldspars and clay minerals by chemical means in rocks. The ultimate result of feeding and then production of waste resulted in favorable conditions for opal formation.

Opal Rings for Men - Tips and Ideas

Opal rings look great on anyone. Most men prefer the large opal solid. If you want to make a statement, the gemstone to go for is the black opal . However, they carry an aspirational price tag.

A man can also go for an inlaid opal or a doublet or solid opal. The majority of opal rings are set with claw settings which are more suitable for women. Men should preferably go for “rub over” settings that appear spartan, sleek and with minimal feminine touch. An opal ring made for a man could be big and diamonds may also be set adjacent to the opal to multiply the opal's appeal.

Boulder Appeal

Men should preferably go for the boulder opal, which is a handsome gem and is perfect for creating opal rings for the masculine sex. Among boulder opals, the undulating opal category is most popular among men. Boulder opal is mined from Queensland in Australia. This type of opal has ironstone as a host rock, and when the ironstone is cut and polished, it transforms into the back of opal solid.

Opal is best set into a 14 carat gold ring as it occupies the perfect place between soft and hard. Nobby opal extracted from Lightning Ridge in Australia is considered the best to set, due to the ability of the opal to display a high dome or cabochon. In the process of cutting and polishing the stone, the cutter decides the way it will bet cut and polished with a dome to acquire the best carat weight and size.

Buying Opal Gemstone

You must take into account the mix of the type of opal, its brilliance, size, pattern and colour. Once you decided on the quality and type of opal, it filters down to selecting the opal colour you find most attractive and one which fits your budget.

• Background colour and type: It is the main factor in determining opal value. Black opal demands a higher price than crystal opal. White or milky opal is the most economical of all opals.
• Size: The bigger the opal the more valuable it is. The unit of measurement is carats.
• Brilliance: The more vibrant the colour, the greater is its value. An opal with a single pulsating colour is more valuable compared to a dull stone with multiple colours.

The price of the opal ring is dependent on the stone type and setting you select.

Opal Engagement Rings - Tips and Ideas

Opal rings are favored as engagement rings as colours bewitchingly appear and disappear to the thrall of the wearer. The gemstone was known from ancient times for its supposedly magical properties.

Heart-seeker

The Greeks considered it as a prophetic stone. According to ancient legend, the Roman senator Nonius elected to choose exile rather than to sell his opal stone to the Roman General Mark Anthony. The General wanted it as his gift to the famed beauty and Egyptian Pharoah Cleopatra.

Opal is known for its intoxicating colours. It is said that no opal stone completely resembles any other in the world. The colours of every opal are unique and exciting. Opal is considered as a harbinger of great fortune.

A Piece of Stunning Distinctiveness

Many couples choose opal as a mark of distinctiveness and to move away from the traditional diamond ring. Since opal is soft, it is supported by a disk to impart protection and showcase the fire within.

White and black opals are known for their stunning sampling of colours. The eye catching fire inside the stone can be made stunningly beautiful if great work is done on it. However, since opal is much softer compared to diamonds (5 or 6 on the Mohs scale compared to the 10 of diamond) and almost equal to glass, the stones need better care to prevent it from being scratched or chipped. It is recommended that tap water be used for cleaning the stone.

The Australian black opal and white fire opal are two of the more popular options for opal engagement rings.

Tips to Help You Select an Opal Ring

If you are choosing for a man, select the bezel or “rub over” setting. The rub over settings protect the opal stone. Gold is molded to form a thin bezel which covers and follows the stone edge, thus protecting the stone from impact and also ensure that the stone remains securely in place.

Boulder opal is sturdier. Queensland boulder opal is comparatively more robust due to its backing of hard natural ironstone and is perfect as an engagement opal ring. Other suitable opals are white opals, crystal opals and black opals. Another advantage of boulder opals is that they allow for more creativity in design. It is advisable to buy a stone which has a low carbochon (dome on top). Stones with high carbochon are more susceptible to impact damage.

In a sentence opals can make for stunning engagement rings, if you make the correct choice and treat the stone with care.

The History of Opal

Opal is regarded as one of five precious gemstones in the world, the other four being emerald, ruby, sapphire and diamond. Like a snowflake, each opal is unique.

Discovery and Beauty

This precious gem is believed to be discovered almost 4,000 years ago and a great number of myths and folklore around it are found in almost all cultures. Opal artifacts in Kenya date about 6,000 years back. Recent archaeological excavations have proved that Aztecs mined opal in Central and South America in the same period.

In Vedic or ancient India, the stone was referred to as a Goddess of Rainbow, who turned to stone. Ancient Arabs believed that opal fell from the sky and the colour play inside it is actually lightning. The Arabs believed that opal has the power to make its wearer invisible.

Opal was believed to have considerable healing powers in a number of world cultures, which persisted to the middle ages. In that time, the stone became known as the Opthalmius or the Eye Stone and many held the belief that it strengthened the eyesight.

Opal and Spain

There is a tale about opal that was very popular in 19th century Spain. The then Spanish emperor King Alfonso XII had been gifted a ring made of opal from an unforgiving Comtesse he had courted previously. The king presented the ring to the queen, his wife, who then died unexpectedly. The ring then passed from owner to owner who all died in mysterious ways. The king himself decided to wear it and he too died. The real reason was the cholera epidemic, but many believed that it was due to the bad effects of the opal ring. The whereabouts of that opal ring remain a mystery to this day.

Opal and Bad Luck

In the 19th century, opal acquired a reputation for bad luck. A number of theories have been cited as the cause, but most historians agree that the cause of all the misplaced notion can be traced back to the Sir Walter Scott authored novel “Anne of Geierstein” in 1829. The public read the first two volumes of the three volume book and mistakenly assumed that since the magic opal mentioned in the book discolours on being touched by holy water then the stone must be cursed. This wrong notion destroyed the sale of opal at that time and prices nearly halved in that period.

Role of Queen Victoria

Queen Victoria did not believe that opals are the carriers of bad luck. She was a great lover of opals and wore them regularly and also gifted them to her daughters. The Queen has been credited with turning the perception of opal around and helping it regain popularity.

South Australian Opal Mining Fields

If one was to value opal only by weight, South Australia would be largest producer of opal in the country. The region is particularly famous for the production of white and crystal opalsthat come from opal fields like Coober Pedy, Andamooka, Mintabie and Lambina.

Coober Pedy Opal Fields

Coober Pedy is known for producing the majority of white opal in the world. The opal mining areas in Coober Pedy lie on South Australia's outback, approximately 750km north of Adelaide. The extremely hot conditions in the region means that most of the locals choose to live underground, where temperatures are lower in summer, and higher in winter. The lack of rainfall and infertile soil that the area experiences does little to spur the growth of plant life in the region. Opal was first discovered here in 1915.

Andamooka Opal Fields

Opal was first discovered in Andamooka by two boundary riders in the year 1930. Changes in the global political climate meant that the field was slow to develop. However, by 1962, it is estimated that over 800 miners had settled here. The Andamooka Fields are located around 520 km north of Adelaide and spans over 52 square kilometers across the Arcoona plateau. Opal is mined from anywhere between three and ten meters down to the ancient seabed. The climate in the area is typically pleasant between the months of March and November. The months between December and February see a significant rise in temperature, and the occasional dust storm.

Mintabie Opal Fields

Opal was first discovered here by a well sinker named Larry O'Toole in the 1920s. Although Mintabie was identified as an opal field during the start of the 20th century, it only became fully active during the late 1970s. The region of Mintabie is located around 180 km south of the Northern Territory Border, 300 km north of Coober Pedy. Mintabie has a difficult climate that is made worse by the lack of water in the region. Temperatures in the area can range from below-zero to the high 40s. This was one of the chief reasons why mining in the area was delayed for so long. Mining in Mintabie takes place via open-cut methods.

Lambina Opal Fields

Opal is rumored to have been discovered in the Lambina opal fields as early as 1930. Extensive mining took place in the late 1980s, but the field has experienced lesser traffic since then. Legislation disallowed mining in the area during the 1990s, but the field has been opened for mining again.

Queensland Opal Mining Fields

Queensland is famous for the production of the boulder opal. Boulder opals are found in deposits of sedimentary ironstone rock native to the western part of the state. The opal fields in Queensland are located within a belt of Cretaceous sedimentary rock formations known as the Winton Formation that spans approximately 1000km.

Queensland's opal mining fields include the Yowah Field, Toompine Field, Quilpie Field, Kyabra-Eromanga Field, Bulgroo Field, Yaraka Field, Jundah Field, Opalton-Mayneside Field and the Kynuna Field.

Boulder opal is abundant in rocks found in these locations. The ironstone boulders that such opals are mined from can vary in size from a handful of centimeters to as large as a car. As such, boulder opals themselves vary significantly in size, with some as large as 20cm being found.

Quilpie Fields

If you are in search of vibrant and colorful opals, your quest ends at the Quilpie Fields. The region is often referred to as the 'home of the boulder opal' as it is considered to be the largest producer of boulder opal in the world. Quilpie is situated approximately 980 km west of Brisbane and 208 km west of Charleville. Quilpie was only officially recognized as a town in the year 1917. The primary industries that make up the Quiplie economy are sheep and cattle farming, oil, gas and opal mining.

Winton Fields

Originally called Pelican Waterhole, the Winton opal fields received its name only in 1875. The town of Winton boasts an eclectic artist community and is also recognized as the 'home' of Australian bush poetry. Winton is also famous for its extensive water supply that makes its way to the Earth's surface through three artesian bores, that are each approximately 1200 metres deep. The region offers stunning landscapes in the form of coloured gorges and ridges.

Opalton Fields

The Opalton field is one of the largest fields in Queensland and has been extensively worked on for many years. Most of the population that resides in this region comprises of miners. Opalton is located only 124 km from Winton. In recent years, Opalton has become a popular tourist hub with many visitors flocking to this area to 'speck' or 'noodle' fragments of opal or ironstone matrix from discarded waste material.

Yowah Opal Fields

As the southern-most opal field in Western Queensland, the Yowah field has also become extremely popular among tourists. The region offers easy access to main roads, shops, fuel services and telephone services and even has its own permanent bore water supply. The Yowah Fields are particularly famous for "Yowah Nuts" These stones can range anywhere between 5mm and 200mm across and have spherical shapes that display concentric bands of light across light or dark ironstone.

New South Wales Opal Mining Fields

New South Wales produces the most valuable kind of opal available in the jewellery market, thereby making it the most important state in Australia, with regard to opal mining. Places like Lightning Ridge are famous for the black opals they produce. White Cliffs is also known for its seam opal, usually white or crystal in appearance.

Lightning Ridge

Lightning Ridge has become so famous precisely because of the black opals found in the area. Black opals are more valuable than other kinds of opals because they have trace elements of carbon and iron oxide within them enhancing the ‘play of colour’. Lightning Ridge is located around 750km from Sydney and has an estimated population of around 3000, made up primarily of miners. Its population varies constantly depending on the number of miners that enter and exit the area.

Geology

Lightning Ridge is particularly known for a geological feature known as the Surat Basin, which is a part of the Great Australian Basin that spans 1.7 million square kilometres. The Basin was formed when sediments settled at the bottom of a large inland sea. These sediments triggered the formation of precious opal.

Since these rocks settled at the bottom of the sea over time, the host rocks are horizontal. The rocks from which black opal is mined, are found in shallow water at the edge of the Basin.

History

Opal was initially discovered in Lightning Ridge as far back as the late 1880s. The first shaft was sunk at the turn of the 20th century by a local named Jack Murray. Over time, more miners began to appear at Lightning Ridge, having tried their luck at White Cliffs. Famous stones like the 822g 'Big Ben' and the 'Flame Queen' are said to have come from Lightning Ridge.

Tourism

Lightning Ridge offers tourists a proper glimpse of the difficult life that miners face. The region plays host to over 90,000 visitors from across the world and there are now a number of motels, gift shops and restaurants in the area. Apart from the stunning scenery that it offers, Lightning Ridge also boasts a diverse wildlife including kangaroos, wallabies, koalas, possums, echidnas and a range of reptiles.

White Cliffs Opal Fields

White Cliffs claims the credit of being Australia's first fully functional commercial opal field. At the start of the 20th century, White Cliffs was considered the largest producer of opal in the entire world. Opal was first produced in White Cliffs in the year 1890. The region's white seam opal quickly entered the markets and rose in popularity. It is estimated that during the late 1890s, there were around 2000 people residing in the area, most of whom were miners. Over the years, White Cliffs has become a popular exploration ground for geologists, palaeontologists, Government bodies and hopeful miners.

Australian Opal Mining Fields

Australia produces 90 percent of all the opal found in the world. Countries like Honduras, Mexico, former Czechoslovakia and Brazil make up for the remainder of opal in the jewellery industry. It is estimated that the Australian export market for opals at the turn of the millennium had a value of $60 million. Between the years of 2000 and 2005, this value rose and varied between $100 and $200 million.

Opal fields in Australia lie predominantly in three states - Queensland, New South Wales and South Australia.

New South Wales - Home of the Black Opal

In terms of actual value, New South Wales is the most important state when it comes to opal. Lightning Ridge is famous for providing the opal market with the finest black opals. What makes the black opal so sought after is the carbon and iron oxide traces in its makeup. White Cliffs is another opal field in New South Wales that is known for its white or crystal opals. Here, 'opal pineapples' are also formed. An 'opal pineapple' is an oddly shaped opal fossil resembling that of a mineral crystal.

Queensland - Boulder Opal Country

Queensland is known for producing boulder opal. Boulder opals are unique in that they are attached to rock like ironstone. Queensland is the only place where boulder opal can be found. Such stones are often found in weathered sedimentary cretaceous rocks. Quilpie is an opal field in Queensland that is the largest producer of boulder opal in the world. Winton is another beautiful region where such opals are found. The Opalton Field, also known as the Fermoy Field is one of the busiest fields in Queensland that tourists often visit to get a firsthand experience of how opal miners go about their business. Finally, the Yowah Opal Field in Queensland is the southernmost opal mining region in the area, famous for opal formation in ironstone nodules that have come to be known as 'Yowah Nuts'.

South Australia - The White Opal Fields

South Australia is the largest producer of opal in terms of volume, with its three main opal mining sites being Adamooka, Coober Pedy and Mintabie. The Andamooka field spans 52 square kilometers littered with shafts, bore-holes and small tunnels. Coober Pedy produces more white opal than any other region. The field is located around 750 km north of Adelaide. Discovered as early as in the 1920s, the Mintabie field was not extensively worked on until the late 1970s. Mintabie is found 180km south of the Northern Territory Border.

Lambina is another opal field in South Australia that many miners claim was the first place that opal was mined. The region experienced rigorous mining during the 1930s and the late 1980s.

How is Opal Mined?

Opal mining in its simplest form can be carried out by a single miner working on his own. A solitary miner digging for opal will use a process known as shaft sinking. This traditional technique involves the use of a shovel and a pick to create a downward shaft. When a miner finds 'opal dirt' located deep within these shafts, the miner will then begin digging sideways in order to determine the 'level' of opal dirt. The sideways digging process may typically involve both picks and small explosive charges. A miner may then use screwdrivers and handpicks to extract opal stones carefully, without causing damage to them.

Drilling

In larger mining processes, a Caldwell-type drill may be used. A Caldwell-type drill is effective in creating deep vertical passages that have a diameter of approximately one metre. Once these holes have been created, a hand windlass connected to buckets will then be used to remove dirt, waste material and mullock. In recent years though, the hand windlass and bucket technique has come to be replaced with power winches and bucket tippers.

While some areas that are excavated may be abundant in opal, there are still a number of difficulties miners face in identifying where to sink shafts. Miners will need to look for 'opal dirt' and then follow 'seam opal' and this is no easy task. Opal lines that begin with potch twists, often change direction and even disappear as a consequence of the high pressures exerted over the years.

Tunneling

The 1970s saw the first use of large tunneling machines to extract opal. These machines incorporate small underground front-end loaders and cutting heads that make it easier and quicker for miners to extract opal. Drilling tests can now be conducted to identify whether certain regions are capable of handling large amounts of pressure and mining. Alternatively, jackhammers, explosives and pickaxes may also be used. Unwanted and valueless rock and soil can be removed with the use of bulldozers.

Opal mining is conducted very carefully in Queensland. The first step of the process involves the strategic removal of rock and stone that places unwanted pressure on ironstone boulders. Once these boulders are excavated, they are sent for processing. Miners at Yowah though, often still use traditional methods like shaft sinking.

When traces of opalization have been discovered on a boulder, it is swiftly removed from the excavated region so that miners can look for further opal content. Opals mined from such boulders retain a thin backing layer of ironstone.

Noodling

Locals also conduct their own form of opal mining by searching for traces of opal in mullock that has been discarded. A noodling machine uses ultra-violet light to inspect mullock in search of opal.

Identifying regions that are rich in opal has become more challenging in recent years, as most productive areas have already been exhausted. Nevertheless, a number of companies continue to undertake well-funded and well-equipped explorations to discover new opal mining sites.

The Most Famous Opals in the World

90 percent of the world's opals are mined in Australia. Naturally, a number of large, fine opals have been discovered here. Here are a few more details on the most famous opals in the world.

The Olympic Australis

Think about an 11-inch-long, 4 ¾-inch-tall and 4 ½-inch-wide opal. Yes, we are talking about the Olympic Australis, the largest gem opal in the world. It has the weight of 17,000 carats (3.45 kg). It is said that more than 7000 carats can be cut from the stone, but the jeweller who owns it, Altmann & Cherny have no intention of cutting it.

The Olympic Australis was found in 1956 at a mine in South Australia's Coober Pedy. That year the Olympic games were being held in Australia, so the miner decided to name the gem after the Olympic games. The Olympic Australis is 99 percent gem and only one per-cent soil. At its last estimation, the gem was valued at AUD2,500,000.

The Aurora Australis

The Aurora Australia is a black opal, and the most valuable in the world at that. The gem was found in Lightening Ridge, in NSW. Altmann & Cherny brought it in a semi rough state and they later cut and polished it into a harlequin pattern. The opal has a black background, interspersed with green, blue and red colours. The gem was named Aurora Australis after the southern lights. The value of the gem is pegged at AUD1,000,000.

The Queen's Opal

The Queen's Opal is also known as the Andamooka Opal. The story of the opal began in 1954, when the South Australian government made it known that it was looking for the best opal ever mined in the opal fields of South Australia to present to the Queen Elizabeth II. The queen was slated to visit Australia for the first time. Altmann & Cherny had submitted a rough opal from a mine in Andamooka. The stone was chosen by the government and it was cut and polished at Altmann & Cherny. Its weight after it was cut was 203 carat and it shone with colours like blue, green and red. It was later set into a palladium necklace.

Pride of Australia/Red Emperor

The Pride of Australia or the Red Emperor was discovered in 1915 at Phone Line. It is called the Pride of Australia because its shape resembles that of the continent. The opal has blue and black veins, interspersed with red streaks. Unfortunately, the Pride of Australia was stolen in 1961 from the Forest Lawn Memorial Museum, USA, where it was on display. It has not been found yet.

The Halley's Comet Opal

The Halley's Comet Opal was named so because it was mined in 1886, when the Halley's Comet was seen. Like the Halley's Comet, which visits the skies over the earth once every 75 years, the Halley's Comet Opal was also a rare find. It is an uncut black opal, the largest one found till date and was unearthed at Lightening Ridge, NSW. In 2006, it was on sale for $ 1.2 million.

A Guide to Common Opal Words

            When you are searching for opals on our site, you may come across many unfamiliar terms. For instance, you might be wondering about the difference between a black opal, a semi-black opal and a white opal. You might have even heard words like floaters, noodling or ratters in relation to opals. Here is a brief guide to the most common terms associated with opals:

Black opal: The most precious form of opal, found mainly in Lightening Ridge, New South Wales. The black body tone comes from a high carbon and iron oxide content. The name is not a reference to the colours displayed by the opal.

Body tone: Opals are rated on a body tone from N1 to N9. Opals having a body tone of N1-N4 are called black opals, those having a body tone of N5-N6 are called semi-black opals and finally, opals having a body tone of N7-N9 are called light opals.

Boulder opal: An opal formed when silica deposits in the cavities and cracks of an ironstone boulder. The ironstone is left on the back and it is cut and polished along with the opal.

Cabochon: Opals are opaque precious stones, so they are given a cabochon cut, unlike transparent precious stones like diamonds which are given faceted cuts. The opal is shaped and polished to give it a domed and convex surface.

Carat: A carat is a unit of weight for a gemstone. One carat is one-fifth of a gram.

Fire Opal: The name 'Fire Opal' is usually used to refer to Mexican Fire Opals. However, any opal that has a brilliant flash or 'fire colours' can be called a fire opal. The name is not commonly used in Australia.

Floater: An opal, which has eroded from its host rock and was found on the surface is called a floater. If found on ground-level, it indicates that there is a source of opal nearby.

Mohs' Scale: An international scale to measure the hardness of a gemstone and distinguish between different kinds of gemstones.

Nobby: An opal which has a natural lump shape is called a nobby. It is found only at Lightening Ridge.

Ratter: A person who poaches opals from someone else's mine. If the person is caught, he could be severely punished.

Rough: A raw opal that has not been cut yet.

Potch: A colourless or common opal. It is non-precious and does not contain any ‘play of colour’.

White opal: An opal which has a body tone of N7-N9 (light or white in colour). It is usually found in South Australia.

How is Opal Valued?

Before you buy opals online, you should have a fair idea of how opals are valued. It can help you make an informed choice. It is quite difficult to make out how much an opal is worth, just by looking at the pictures online. An honest dealer will allow you to return an opal or will give you more details on the stone. The opal should have been objectively graded and should come with a certificate of authenticity. Here are a few details on how opals are valued.

Opal Class

The first thing you should look for is the class. There are basically three classes of opals- solid opals, doublet opals and triplet opals. Doublet and triplet opals contain only a thin slice of precious opal and so are cheaper than solid opals.

Type of solid Opal

If you want to buy a solid opal, then the major factors that you should consider are the body tone, weight of the stone and pattern and brightness of the stone.

Body Tone of the Opal

The body tone is the most important factor in the valuation of an opal. Based on the body tone, there are three types of opals. They are black opals, semi-black opals and light opals and these are measured on a scale between N1 and N9. Generally, the darker the body tone, the more valuable the opal. So black opals are more precious than semi-black opals, which are in turn more valuable than light opals.

The Flashes of Colour in the Opal

The flashes of colour in the opal is also called 'play of colour'. The flash is created when light hitting the opal gets diffracted. A stone with a red/orange flash is more valuable than a stone with a green flash, which is again more valuable than a stone with a blue flash.

Brilliance or Colour Clarity

The brilliancy or clarity of the colours of the opal is also taken into consideration when valuing the opal. This can range from brilliant, subdued to dull.

The Pattern of Colours

A precious opal will have some unique coloured segments. The colour displayed or the distinctiveness of the pattern will also determine the value of the opal. The most common patterns are harlequin, flagstone, ribbon, straw, Chinese writing and picture stones. Other patterns are floral, rolling flash, broad flash and pinfire.

Some other factors like the colour bar thickness and faults (if they exist) are also considered to decide the value of the opal. Note that the best opals come from Australia, which produces 90 percent of the world's supply of opal. You may be tempted to buy an opal on eBay or a similar site where the prices might be unbelievably low. But there is no free lunch and there is chance that the dealer may actually be quoting the price for a synthetic opal or a doublet or triplet opal. It is best to buy opals from a well known dealer.

How to Buy Opals- A Guide to Buying Opals

Buying an opal is not an easy job, especially if you do not know much about opals. To make it easy and to help you make the right choice, here is a small guide on how to buy opals.

First, you will have to decide whether you want to buy a solid opal, a doublet opal or a triplet opal. A solid opal, though more expensive, is the real deal and is the best investment. Doublet and triplet opals contain only a thin piece of opal. These are relatively inexpensive and can be easily damaged, sometimes even by immersing in water. There are various kinds of solid opals such as black opals, semi-black opals, light opals, crystal opals and boulder opals. Of these, black opals are the best looking and most expensive.

Nearly all the world's supply of black opals comes from just one place in New South Wales, called Lightening Ridge. Black opals come in three body tones- N1, N2, N3. So if you are buying an N1 opal, you are buying the best variety of black opals available. If you are buying a N4 opal, you are actually buying a semi-black opal and if you buying a N9 opal, you are investing in a light or a milky white opal.

Crystal opals are more translucent and transparent than other types of solid opals. These opals are highly valued if they have a strong play of colours. A boulder opal is a cousin of the black opal, which contains an ironstone base.

Other Factors to Consider When Buying Opals

Opals have individual personalities, just like people. No two opals in the world are identical. The most important factor is the body tone of the opal. But there are many other factors to be considered as well. After all, the stone must appeal to you!

The other important factors are the play of colours, brightness, base density, colour intensity, the weight of the stone, the shape of the opal, flaws, the region where the opal was mined and finally the cost of the jewellery in which the opal is set.

Are Opals Bad Luck?

The opal is one of the most controversial gemstones in history. For hundreds of years, the opal has been unfairly berated as a harbinger of bad luck and there are many old wives' tales about its purported evil qualities. But if you ask us, the opal is one of the best and luckiest of gemstones. If they bring bad luck, how do you account for the success we have enjoyed cutting and selling opals for the past 40 years? How do you explain the success of so many opal miners who have made fortunes from these stones and are now living prosperous lives?

How the Opal Came to Be Vilified

We are living in an age of science and reason so superstitions concerning the opal have more or less disappeared. But, when it comes to opals, some of that old stigma exists even now.

Historically, gemstones were valued for their brilliance and the magical qualities they were said to possess. They were used as a remedy for all sorts of afflictions like baldness, impotence, alcoholism and more. Some precious stones like the emerald were thought to increase intelligence, while rubies were a defense against misfortune. But the poor opal was vilified as a companion of sorcerers and witches, who used the gemstone to cast curses on other people and bring death. The brilliance that should have been hailed, was compared to the eyes of cats, snakes and toads, who were said to be the devil's familiars.

Jewelers were especially averse to the opal because it is a fragile stone and may break if it is mistreated. So they did not like to work on an opal since it could fracture and they would have to pay the owner for the losses. Diamond merchants were also responsible for the notoriety that the stone acquired. When the diamond merchants came to see that high quality opal was being mined in Australia and it was flooding the market, they saw it as a threat to their hegemony of the gemstone business.

The Opal was Valued in Antiquity

Did you know that the ancient Romans prized opals? It was considered as a symbol of good luck and Caesars even gave them to their wives for good fortune. The opal was second only to the emerald, in terms of value. The Romans even carried opals on their person as a good luck talisman, because it was thought be a manifestation of the rainbow. One Roman senator named Nonius was even sent to exile when he refused to give Marc Anthony his precious opal, who wanted to present it to Cleopatra. The early Greeks credited the opal with bestowing the power of prophesy and foresight on the wearer.

In the Middle Ages, the opal came to be called the eye stone, because it was said to impart good eyesight to the wearer. Women with blonde hair even wore opal necklaces because it was thought that it would help them maintain the colour of their hair. So you see, opals are not bad luck at all.

How to Care for Opals

 

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It is first important to understand that there are different kinds of opals, and each of them need to be treated differently:

Doublets

Doublets are made up of two individual layers. The first layer is black backing that is usually made of some black industrial material or black potch (colourless opal). The second layer is a thin slice of opal.

Triplets

Triplets are made up of three distinguishable layers. The first is the black backing, the second layer that lies in between is a thin slice of opal, and the third layer is that of reflective glass or quartz that protects the opal, as well as magnifies the light being reflected through it.

Solid Opal

Solid opal is the most valuable kind of stone and is made up only of naturally mined and cut opal.

Caring for your Opal

It is always recommended to clean solid opal by using a mild detergent and a soft damp cloth. Immersing it any kind of liquid does nothing to prolong its life. It is not advisable to use heavy-duty chemical detergents or cleaners when cleaning your opal. Doublets and triplets must never be immersed in any liquid as this may affect the adhesive that holds the different layers together.

It is also not recommended to use any kind of ultrasonic cleaner when cleaning your opal as these vibrations may cause cracks in the stone.

In the event that your opal has lost its colour, or gotten scratched, you may be wise to take it to an opal cutter immediately. Professionals will polish your opal and bring it back to its original condition. 

Storing Opals

Storing your opal need not be a difficult task. If you are not planning on wearing your opal stone, you can simply place the stone within a padded cloth bag and store it wherever you wish. It is advisable to use a padded bag because it will offer your stone some protection from drops or impacts. In cases where the stone is going to be stored for prolonged periods, using cotton wool dabbed in a few drops of water to wrap and seal it is effective. The water is not meant to seep into the stone but prevent water from coming out of the stone in the event that it is exposed to conditions of low humidity.

How to clean your Opal Jewelry

1. polish directly on jewelry (use when jewelry is dry)
2. follow with dry clean cloth or tissue
3. in case of wearing or containing food, rinse with water or clean with normal detergent
4. if silver jewelry still be dirty, you can repeat whole process again, until it is cleaned