- Formation: Opals are formed from silica, the same material found in sand. When water seeps down through the earth, it picks up silica from sandstone. This silica-rich solution eventually finds its way into cracks and voids in the ground.
- Deposition: As the water evaporates, it leaves behind a silica deposit. Over many millions of years, layer upon layer of silica builds up, eventually creating opal.
- Structure: The silica particles in opal are arranged in a grid-like pattern. This structure causes light to diffract, creating the play of colours that opals are famous for. The size and arrangement of these silica particles determine the colour and pattern of the opal.
- Environment: Australia's unique geological conditions, particularly in places like Coober Pedy, Lightning Ridge, Grawin and Andamooka, provide the perfect environment for opal formation. These areas were once ancient seabeds, which allowed for the necessary water and silica interaction over millions of years.
The result is the beautiful and diverse range of opals that Australia is known for. Each opal is unique, with its own pattern, colour, and character, making it a truly special gemstone.
3) What is potch or common opal?
Potch opal, also known as common opal, is a type of opal that lacks the play-of-colour seen in precious opals. Here are some key points about potch opal:
- Appearance: Potch opal is usually translucent or opaque with a white, milky, or even grey appearance. It doesn't exhibit the vibrant flashes of colour that precious opals do.
- Composition: Like all opals, potch opal is made of silica. However, the silica spheres in potch opal are either absent, too small, or irregularly arranged, which prevents the formation of colour.
- Uses: Despite its lack of colour, potch opal is still valued for its unique beauty and is often used in jewellery-making. It can be carved into various shapes, polished into beads, or used as a base for doublets.
- Locations: Potch opal can be found in various parts of the world, including Australia, Mexico, Brazil, and Ethiopia.
- Value: The value of common opal (potch opal) is generally much lower than that of precious opals due to its lack of play-of-colour. On average, common opals can range from a $1 to around $10 per carat
While it may not have the same visual appeal as precious opals, potch opal still holds its own charm and is appreciated for its unique qualities.
4) What is black opal?
Black opal is one of the most precious and valuable types of opal.
- Colour and Appearance: Black opal is known for its dark body tone, which can range from dark grey to jet black. This dark background makes the vibrant play-of-colour with flashes of bright, vivid colours stand out more dramatically compared to other opals.
- Play-of-Colour: The play-of-colour in black opal can include a spectrum of hues, from reds, blues, and greens to yellows and purples. The more intense and diverse the colours, the more valuable the opal.
- Origins: The most famous and significant source of black opal is Lightning Ridge in New South Wales, Australia. This region is renowned for producing some of the finest black opals in the world.
- Value: Due to their rarity and stunning appearance, black opals are highly sought after and can command high prices. The value of a black opal is determined by factors such as the brightness and pattern of the play-of-colour, the quality of the cut, and the size of the stone. On average, black opals can range from a $300 to $10,000 per carat which makes them as valuable as diamonds if not more
- Use in Jewellery: Black opals are often used in high-end jewellery, such as rings, pendants, and earrings, where their striking colours can be showcased to full effect.
Black opals are truly unique and captivating gemstones, admired for their beauty and rarity.
5) What is crystal opal?
Crystal opal is a stunning type of opal characterized by its transparency or translucency, which allows light to pass through the stone.
- Clarity: Crystal opal ranges from completely transparent to semi-transparent. This clarity allows for a striking play-of-colour to be seen throughout the stone, often giving it a vibrant and lively appearance.
- Play-of-Colour: Just like other opals, crystal opal displays a mesmerizing array of colours. The transparency of the stone can enhance the visibility and intensity of these colours, making the patterns and flashes more noticeable.
- Body Tone: The body tone of crystal opal can vary from clear to a light or milky base, but what sets it apart is the degree of transparency rather than the base colour itself.
- Origins: Crystal opals are found in several regions, with notable sources including Coober Pedy and Andamooka in South Australia, as well as Lightning Ridge in New South Wales.
- Value: The value of crystal opal can vary significantly based on several factors, including its clarity, colour, size, and cut. High-quality crystal opals with exceptional clarity and vibrant play-of-colour can fetch higher prices. Generally, crystal opals are valued between $100 to $5,000 per carat.
- Use in Jewellery: Due to their striking appearance, crystal opals are highly valued in the jewellery market. They are often used in high-end pieces such as rings, pendants, and earrings, where their vibrant colours and clarity can be showcased.
Crystal opal is cherished for its unique ability to combine clarity with a stunning display of colours, making it a prized gem for both collectors and jewellery enthusiasts
6) What is boulder opal?
Boulder opal is a unique and captivating variety of opal.
- Formation: Boulder opal forms as thin seams or patches of precious opal within or attached to its host rock, usually ironstone or sandstone. The opal is found in cracks and cavities within these rocks.
- Appearance: Unlike solid opals, boulder opals are cut with a thin layer of the host rock left on the backside, enhancing their natural and rustic appearance. The opal can display a range of hues, including blues, greens, reds, and yellows, often with a play of colours that seems to dance and shimmer when viewed from different angles.
- Stability: The presence of the host rock provides added stability to the opal, making it less prone to damage compared to other types of opal. Locations: Boulder opal is primarily found in Queensland, Australia, with notable sources around Winton, Quilpie, and Yowah. It can also be found in other locations such as New South Wales, Canada, and Brazil.
- Value: The value of boulder opal can vary widely based on several factors, including its colour, pattern, clarity, and the amount of ironstone present. High-quality boulder opals with vibrant colours and intricate patterns can command higher prices sometime as high as black opal. Generally, boulder opals are valued between $20 to $10,000 per carat.
- Use in Jewellery: Boulder opals are highly prized by collectors and jewellery enthusiasts for their beauty and rarity. They are often used in jewellery, where their natural and rustic appearance is showcased.
7) What is white opal?
White opal, also known as milky opal, is one of the most common types of opal.
- Appearance: White opals have a light or white body tone, which provides a pale backdrop for their play-of-colour. The colours can range from soft pastels to vibrant flashes, but the lighter base tone generally makes the colours appear more subdued compared to darker opals.
- Body Tone: The base colour can vary from almost transparent to a milky white, which is why they are sometimes referred to as milky opals.
- Play-of-Colour: Despite their paler background, white opals can still display a beautiful array of colours, including reds, greens, blues, and more. The play-of-colour is caused by the diffraction of light through the silica spheres in the opal.
- Origins: White opals are primarily found in Australia, with significant deposits in Coober Pedy, Andamooka, and Mintabie.
- Value: While typically less valuable than black opals due to the more subdued play-of-colour, high-quality white opals with bright and vibrant colours can still be quite valuable. The value depends on factors like colour intensity, pattern, and the quality of the cut. Generally, boulder opals are valued between $10 to $500 per carat.
- Use in Jewellery: White opals are popular in jewellery and are often used in rings, pendants, earrings, and more. Their lighter base tone can make them versatile and elegant for various designs.
8) What type of opal do you sell?
At DNF JEWELLERS, we exclusively offer solid, untreated opals, renowned for their natural beauty and unparalleled play-of-colour. Each gem is meticulously sourced to ensure authenticity and quality, showcasing the finest specimens from Australia's rich opal fields. Our deep connections with local Australian miners and communities allow us to bring you the very best opals, celebrating the unique characteristics of each gem and making every piece a one-of-a-kind treasure
9) What is treated opal?
Treated opal refers to opal that has undergone various processes to enhance its appearance or durability. Here are the most common types of treatments:
- Doublet: Doublet opal is a type of enhanced opal that consists of a thin layer of precious opal usually crystal or white opal glued onto a dark backing, often made of ironstone or potch opal. This dark backing enhances the colour and makes the play-of-colour more pronounced. Doublet opals are generally more affordable than solid opals and are a great way to enjoy the beauty of opal without the higher cost
- Triplet: A triplet opal is a composite gemstone comprising three layers: a top layer of clear quartz or glass, a middle layer of thin, precious opal, and a bottom layer of dark backing often black potch or ironstone. The clear top layer protects the opal and enhances its vibrancy, while the dark backing accentuates the opal's play-of-colour. Triplet opals are more affordable than solid or doublet opals, as they use a small amount of precious opal
- Dyeing: Some opals, especially common or white opals, may be dyed to enhance or change their colour. This can make them appear more vibrant and appealing.
- Smoke Treatment: This involves exposing the opal to smoke, which can penetrate the stone and darken its body tone, making the play-of-color more pronounced. This is often done with Ethiopian opals.
- Sugar Treatment: This process involves soaking the opal in a sugar solution, followed by a bath in sulfuric acid. The acid reacts with the sugar to create dark carbon deposits within the opal, enhancing its colour contrast.
- Coating: Some opals are coated with a clear resin or other materials to improve their appearance and protect them from damage. This can add a layer of protection and enhance the stone's luster.
- Stabilization: This involves impregnating the opal with a resin or other stabilizing agent to make it more durable. This is commonly done with opals that have a tendency to crack or craze.
10) Australian opal VS Ethiopian opal
Australian opals and Ethiopian opals each have their own unique characteristics and appeal. Here's a comparison to help you understand the differences:
Australian Opals
- Origin: Australia is the world's leading producer of opals, contributing around 95% of the global supply.
- Types: Includes black opal, white opal, boulder opal, and crystal opal.
- Play-of-Colour: Australian opals are known for their vibrant and stable play-of-colour, with a wide range of hues.
- Durability: Generally, more stable and durable, with fewer issues related to water absorption.
- Value: Typically, higher in value due to their quality and reputation.
Ethiopian Opals
- Origin: Ethiopia is a newer player in the opal market, with significant deposits found in the Wollo Province.
- Types: Includes hydrophane opals, which can absorb water and change appearance.
- Play-of-Colour: Ethiopian opals are known for their striking play-of-colour and unique patterns.
- Durability: Can be less stable due to their hydrophane nature, which can lead to cracking and crazing.
- Value: Generally, less expensive than Australian opals, but still highly valued for their beauty.