Types Of Opal

Several types of opal exist, each with its own unique characteristics and qualities. Here are some of the most common types of opal:

1. White Opal: This type of opal has a white or light-coloured body with flashes of colour throughout. It is often found in Australia.

2. Black Opal: Black opal is characterized by a dark body colour that enhances its vivid colour play. It is the rarest and most valuable type of opal and is primarily found in Australia.

3. Boulder Opal: Boulder opal is formed when thin veins of opal are found in ironstone boulders. The opal veins are often surrounded by a matrix of brown or black ironstone.

4. Crystal Opal: This type of opal is transparent or translucent and has a crystal-like appearance. It is often found in Australia.

5. Matrix Opal: Matrix opal is formed when opal is deposited in the pores and cavities of host rocks. The opal forms a matrix around the host rock, creating a unique pattern.

6. Fossil opal, also known as opalized fossils or opal fossils, is a type of opal that has replaced the organic material of a fossil over time.

7. Fire Opal: Fire opal is characterized by its fiery orange or red body colour. It is typically found in Mexico.

8. Ethiopian Opal: Ethiopian opal is a relatively new discovery and is known for its bright colours and translucent body. It is found in Ethiopia.
   

These are just a few examples of the types of opal that exist. Each type of opal has its own unique characteristics and value, and opal enthusiasts often have their own preferences and favourites.

White Opal

White opal is a type of opal that has a white or light-coloured body with flashes of colour throughout. It is one of the most common and widely available types of opal, and is found primarily in Australia.

White opal is formed when water seeps into cracks and voids in rocks and deposits silica spheres. These silica spheres diffract light, creating the iridescent colours that opal is known for. The colour play in white opal is often less intense and more subdued than in other types of opal, but it can still be quite beautiful.

White opal is often used in jewellery, particularly in more affordable pieces, due to its relatively low cost compared to other types of opal. It is also used in decorative objects and inlays, such as for boxes and tableware. The value of a white opal depends on the intensity and distribution of its colour play, as well as its size and overall quality.

Black Opal

Black opal is a type of opal that is characterized by its dark body colour, which enhances its vivid colour play. It is considered the rarest and most valuable type of opal, and is primarily found in Australia, particularly in the Lightning Ridge area of New South Wales.

Black opal gets its colour from the presence of iron oxide and other minerals in the silica spheres that make up the opal. The dark body colour can range from grey to black, and it can have flashes of any colour of the spectrum.

The value of black opal is determined by several factors, including the intensity and distribution of its colour play, the thickness of the opal, and the overall quality of the stone. Black opals with darker body colour and more vivid colour play are generally considered to be more valuable.

Black opals are highly prized by collectors and jewellery designers for their beauty and rarity. They are often used in high-end jewellery pieces, and can command very high prices due to their scarcity and beauty.

Boulder Opal (My Favorite)

Boulder opal is a type of opal that is found in ironstone boulders, typically in Australia. It is formed when thin veins or patches of opal are found within the host rock. The opal forms as a thin layer or coating on the surface of the ironstone, creating a unique and striking pattern.

Boulder opal is characterized by its earthy tones and its combination of opal and ironstone. The ironstone matrix can range in colour from brown to black, and can be interwoven with veins of opal in a variety of patterns.

Boulder opal is highly valued for its unique and natural beauty, and is often used in jewellery and decorative objects. It can be cut and polished into various shapes and sizes to highlight the beauty of the opal and the matrix. The value of boulder opal depends on the quality of the opal and the pattern and colour of the matrix, with pieces that have larger and more colorful opal veins generally being more valuable.

Crystal Opal

Crystal opal is a type of opal that is characterized by its transparency or translucency, giving it a crystal-like appearance. It is formed in a manner similar to other types of opal, through the deposition of silica spheres in voids and cracks in rocks. However, in crystal opal, the silica spheres are more densely packed and more regularly arranged than in other types of opal, which gives the stone its transparency.

Crystal opal can come in a variety of colours, including white, grey, blue, green, and red, and it often has a bright and vivid colour play due to the transparency of the stone. It is found primarily in Australia, particularly in the Lightning Ridge area of New South Wales.

Crystal opal is highly prized for its unique and beautiful appearance, and is often used in high-end jewellery and decorative objects. The value of crystal opal depends on the intensity and distribution of its colour play, as well as its transparency and overall quality. Pieces that have a more intense and varied colour play are generally more valuable.

Matrix Opal

Matrix opal is a type of opal that is formed when the opal forms as small fragments or veins within a host rock, such as sandstone or ironstone. The opal is typically not continuous, but rather occurs as small patches or fragments that are scattered throughout the matrix rock.

Matrix opal can display a range of colours and patterns, depending on the type of host rock and the quality and quantity of the opal fragments. It can have a dark or light background, and the opal fragments can range in size and colour from small and sparse to larger and more densely packed.

Matrix opal is often used in jewellery and decorative objects, and is prized for its unique and natural beauty. It is found primarily in Australia, particularly in the Queensland and South Australia regions. The value of matrix opal depends on the quality and quantity of the opal fragments, as well as the overall appearance of the stone. Pieces with a larger and more dense distribution of opal fragments are generally more valuable.

Fossil Opal

Fossil opal, also known as opalized fossils or opal fossils, is a type of opal that has replaced the organic material of a fossil over time, preserving the shape and structure of the original organism. The process of fossilization occurs when mineral-rich water seeps into the pores and cavities of a fossil, replacing the original organic material with silica or other minerals.

Fossil opal can be found in a variety of organic materials, including wood, shells, bones, and teeth. The opalization process can create a wide range of colours and patterns within the fossil, and can enhance and preserve the details of the original organism.

Fossil opal is highly prized by collectors and jewellery designers for its unique and natural beauty, and is often used in high-end jewellery and decorative objects. It is found primarily in Australia, particularly in the Lightning Ridge area of New South Wales.

The value of fossil opal depends on the quality and rarity of the fossil, as well as the quality and appearance of the opalization. Pieces with a more complete and well-preserved fossil, as well as those with a more vivid and distinct opalization, are generally more valuable.

Fire Opal

Fire opal is a type of opal that is known for its vivid orange, yellow, or red body colour, which gives it a fiery appearance. It is formed from silica deposits that contain iron oxide, which gives the stone its distinctive colour.

Fire opal is typically found in Mexico, but it can also be found in other parts of the world, including the United States, Australia, and Brazil. It is often found in volcanic rock formations, and is sometimes referred to as "Mexican opal" or "Czech opal" depending on its origin.

Fire opal is highly prized for its intense colour and transparency, and is often used in jewellery and decorative objects. It can be cut and polished into various shapes and sizes, and is particularly popular for use in pendants, earrings, and other pieces where the colour and transparency of the stone can be fully appreciated.

The value of fire opal depends on the intensity and consistency of its colour, as well as its transparency and overall quality. Pieces with a more intense and consistent colour, as well as those with fewer inclusions or imperfections, are generally more valuable.

Ethiopian Opal

Ethiopian opal is a type of opal that is found in Ethiopia, primarily in the Wello Province. It is a relatively new discovery, with mining of the stone beginning in the 1990s.

Ethiopian opal is known for its bright and vivid colours, including flashes of red, green, blue, and orange. It is formed from silica deposits in volcanic ash and is characterized by its translucency and play of colour.

Ethiopian opal can be found in a range of qualities, from opaque to transparent, and can be cut and polished into various shapes and sizes. It is highly valued for its unique and vibrant colours and is often used in jewellery and decorative objects.

The value of Ethiopian opal depends on the intensity and distribution of its play of colour, as well as its transparency and overall quality. Pieces with a more vibrant and varied play of colour, as well as those with fewer inclusions or imperfections, are generally more valuable.

Inclusions

Inclusions are natural imperfections or internal features within the structure of the opal. While some inclusions can enhance the beauty and uniqueness of an opal, others can detract from its value and desirability.

Inclusions can devalue opals in several ways:

1. Appearance: Inclusions can make an opal appear cloudy or dull, which can significantly reduce its visual appeal.

2. Colour: Inclusions can affect the colour play and brightness of an opal. If the inclusions are too large or too dark, they can block the light from passing through the stone, causing the colour play to be muted or nonexistent.

3. Durability: Some inclusions can weaken the structure of the opal, making it more prone to cracking or chipping. This can make the opal less valuable and less desirable for use in jewellery.

4. Rarity: Inclusions can also affect the rarity of an opal. If the inclusions are too common or not unique, they can reduce the overall value of the stone.

Overall, inclusions can affect the appearance, colour, durability, and rarity of an opal, which can all impact its value. However, not all inclusions are bad - some inclusions can add character and uniqueness to opal and may be desirable to some buyers. It ultimately depends on the individual preferences of the buyer and the overall quality of the opal.

Grading Opal

Opals are graded based on a combination of factors, including colour, pattern, transparency, and overall appearance. The grading process can vary depending on the specific type of opal and the individual or organization doing the grading, but here are some general factors that are typically considered:

1. Body Tone: The body tone of an opal refers to the background colour of the stone, which can range from black to white, and everything in between. Black opals with a dark body tone are generally considered the most valuable.

2. Colour: Opals can display a range of colours, from red and orange to blue and green. The intensity, brightness, and saturation of the colours can all impact the overall value of the stone.

3. Pattern: The pattern of an opal refers to the way the colours are distributed and arranged within the stone. Some patterns, such as harlequin or rolling flash, are considered more desirable than others.

4. Transparency: The transparency of an opal refers to how much light passes through the stone. Opals with high transparency and a clear body are generally more valuable than those with cloudy or opaque bodies.

5. Shape: The shape of an opal can also impact its value. Stones that are well-rounded and symmetrical are typically more desirable than irregularly shaped stones.

Grading opals can be a complex process that requires a trained eye and expertise in the field. Some various organizations and laboratories specialize in opal gradings, such as the Gemological Institute of America (GIA) and the Opal Association in Australia. Ultimately, the value and quality of opal will depend on its individual characteristics and the preferences of the buyer.

Not Always about the Weight

Opals, like other gemstones, are typically weighed in carats. One carat is equivalent to 0.2 grams or 0.007 ounces. Opals can range in size and weight, from small chips to large stones weighing several carats or more.

To weigh an opal, jewelleers and gemologists use a sensitive digital scale that can measure weight to the nearest hundredth of a carat. The opal is carefully placed on the scale, and the weight is recorded.

It's important to note that while weight is a factor in determining the value of opal, it's not the only factor. The quality and beauty of the stone, including its colour, pattern, and transparency, can also impact its value. In addition, opals can be cut and shaped in different ways to maximize their beauty and value, regardless of their weight.