The value of an opal is determined by a variety of variables. The opal type, body tone, brightness, pattern, color bar thickness, color play, and flaws all play key roles in determining the value. Other crucial considerations include the quality of the cut and polish, as well as the size of the stone. Large stones can be more valuable than small ones.
Cheap opals are mostly from Burma (also known as Myanmar) or Australia. They are called "cabbage" for the resemblance they bear to headstones. These stones are found in the ground and usually have roots still attached. They are mined and processed without regard to conservation practices. As a result, many cabbage opals are actually pale copies of the flower pattern. Others are completely matrixed (i.e., filled with mineral matter). Still others have their colors bleached out by heat or chemicals used during processing.
High-end opals come from Australia, India, Pakistan, Russia, and Afghanistan. They are generally larger than cabbage opals and often have greater potential value. High-quality cutting and polishing can increase their value significantly.
Medium-range opals come from Brazil, China, Colombia, France, Indonesia, Japan, Mexico, New Zealand, Nigeria, South Africa, Thailand, and the United States. They are usually smaller than Australian opals but larger than cabbage opals.
People believed that a cut and polished opal would have the attributes of any other stone with which it had a color—for example, a blue opal would be akin to a sapphire. Opal is a challenging stone to work with since it often shatters when cut or mounted in jewelry. This may not be desirable if you want the piece to look like glass.
In ancient times, opals were thought to have magical properties. They could protect against the evil eye, help find love, and heal wounds. Today, they are still considered a good-luckstone.
There are two main types of opals: fire-opal and earth-opal. Fire-opals are red, brown, or yellow and are formed when minerals such as iron oxide combine with water to create a gelatinous mass that cracks and dries into stones. Earth-opal are green, blue, gray, or white and are created when minerals such as silica and alumina combine with water to form a rock that gets folded and carved by underground currents.
Opals are found in many different countries. However, the majority of American opals come from Arizona. There are also mines in Canada, India, Indonesia, Russia, South Africa, and Australia.
Miners use different methods to find opals.
Opals with a black or dark body tone are often more valued than those with a white, light, or crystal body tone, since a darker body tone displays colors more vividly. Black opal is the most valuable form of opal, with prices exceeding $10,000 USD per carat. Pink, red, and blue opals are also prized by collectors.
An opal's color comes from microscopic bubbles of gas trapped inside the stone as it forms. The color can be any natural substance that provides enough mass to create a gem-quality bubble. Most commonly, this is carbon dioxide dissolved in water under high pressure. The gas escapes through weak spots in the rock when the pressure drops, at which point the stone begins its life as an opaque mineral.
The quality of an opal depends on how much color is present and how true these colors are to their original source material. For example, green and yellow opals tend to be less valuable than brown or red ones of the same quality. The deeper the color, the higher the value too! Black opal is worth more than white opal of equal size because it has more visible color and better clarity to boot.
Opal was one of the first gemstones used by humans. It was given as royal gifts and worn as jewelry, especially by women.
Value. White opals, on the other hand, are the least valued type of opal. Opals with an extremely white body tone are likewise quite light in color. Good grade white opal, on the other hand, may be extraordinarily stunning and can command prices of up to AUD $200 per carat. The highest quality white opal has a golden-yellow undertone and can be almost as rare as blue opal.
The rarity of good quality white opal makes it expensive too. You can expect to pay between $20,000 and $50,000 or more for a 1-carat stone.
Weight. White opal ranges in weight from about 10 grams (0.35 oz) to over 50 grams (1.8 oz). The average weight is about 20 grams (0.7 oz).
Color. White opal comes in various colors including pure white, yellow, orange, red, brown, black, gray, and green. It's also possible to find stones that are split into two or more colors - usually dark blue and light blue, dark red and light red, or yellow and white. These split stones are very rare though.
Texture. Opal tends to be rough and jagged but fine quality stones can be smooth. Sometimes pieces contain natural fissures or cracks which can be beautiful if they're open-ended or framed.
Opal is undoubtedly the most distinctive, diversified, and lovely birthstone. Opal, unlike other gemstones, is amorphous, which means it lacks a distinct crystalline structure. It takes on many different shapes and hues, making it rather surprising. The word "opal" comes from the Greek ophis (οφίς), which means "serpent". This makes sense since the first opals were discovered in Persia where they are called "Ophiuchus" after one of the Greek gods.
In mythology, Ophius was the father of Euanthes who became the king of men under the name Auanthes. He was also the husband of Pallas Athena who bore him three children: Aglaurus, Euneos and Thoon. After the death of Ophius, his wife married her son Aglaurus to obtain sovereignty over Athens. When Euneos and Thoon grew up, they fought against their mother for the throne but she killed them both. Only Aglaurus survived this tragedy and he too died young. His body was placed in the temple of Athena Polias (the Ancient Greek name for Athens) where priests used to burn bones to help cure people of diseases. That's why archaeologists call the period between 750 and 550 BC the "Burning Period".
Choosing a Size The larger the fire opal, the higher the price. This is due not just to the sheer size of the stone, but also to the fact that bigger gemstones are more rare (and they often cost more per carat).
Fire opals are very hard to work with and rarely find their way into jewelry. This means there is no supply and demand for these stones, so their value stays fairly constant.
The color of fire opals varies but generally falls in the red or orange spectrum. They can be brown or black if exposed to enough heat over time. Sometimes white flashes will appear within the stone when it is heated above a certain temperature.
There are two main types of fire opals: natural and cultured. Natural fire opals contain only carbon inside their crystals and are considered raw materials because they need to be heated above 500 degrees Celsius (932 degrees Fahrenheit) to release the color within them.
Cultured fire opals contain other elements too, but mostly silicon and oxygen. These gems can already be colored after being mined and are usually used as beads or components of jewelry made from silver or gold. However, diamonds can also be cultured from coal tar which is another type of fossil fuel. Scientists have been able to create diamonds with different colors by using different concentrations of blue carbon compounds in the lab.