Opal is a gorgeous semi-precious gemstone that has been alluring people for centuries with its distinct beauty. It is famed for showcasing a vivid play-of-color that has often been compared to the galaxy, a rainbow and fireworks. The term ‘play-of-color’ can be described as an optical phenomenon that causes the gem to flash various hues and patterns when it is moved or due to a reaction with light. This characteristic makes each opal different from the other.
This stunning gem is closely related to the quartz mineral, and its chemical composition includes millions of tiny, amorphous silica spheres. These spheres cause the stone to diffract light and take on numerous colors from different angles. In addition to the size of the silica spheres, the proportion of other minerals mixed within the stone is responsible for the opal’s color. Hence, you can find this stone in a variety of hues, such as black, brown, pink, red, blue, white and more.
While green, white and blue-toned opals are commonly available, the ones that display black and red hues are extremely rare. Most opals are fairly opaque, but it’s possible to find some that are more transparent than the others. Some of the most popular types of naturally occurring opals are boulder opal, black opal, white opal, matrix opal, crystal opal and fire opal.
As with all gems, synthetic and imitation opals can be found in the market, however readily available and naturally occurring opals get more preference. Approximately 97% of the world's opal supply comes from Australia, and it’s also the national stone of the country. This gem is also mined in Mexico and several other countries across the globe.
There are not many gemstones that have folklores as rich as an opal does. Throughout the ages, opal was considered to be a powerful stone that induced mystical vision and enhanced creativity.
The Aboriginal tribes from the Andamooka region in South Australia believed that an opal was born from a rainbow that was brought to the earth by the creator of Dreamtime; a term used by Aborigines to describe the relationship between the natural, spiritual and moral elements of the world. The creator returned to heaven after he conveyed to mankind his hopes for eternal peace. The rock he stood upon absorbed all the colors of the rainbow and turned it into a beautiful opal.
The Romans associated opal with fidelity, hope and purity, while the early Greeks believed it could foretell the future. East Asians revered it as a sacred stone and the Arabs believed that opal came from heaven.
This stone’s popularity dwindled considerably when author Sir Walter Scott’s novel "Anne of Geierstein" was published in the year 1829. The story gave the impression that opal was demonic and wearing it would bring bad luck. It is believed that this caused the opal market to crash and the gem’s price dropped by almost 50 percent.
It regained popularity within a short period of time when Queen Victoria of England laughed at the superstitions that were associated with the stone. She and Napoleon Bonaparte were some of the famous admirers of opal. In fact, it is said that the Queen was so fond of the stone that she gifted them to her daughters as wedding gifts. Today, opal continues to lure people with its sheer beauty.
Hardness & Strength
Opals are delicate and score a rating of 5.5 - 6.5 on Mohs scale of mineral hardness, which means they are susceptible to scratches and breakage. Shallow crazing (surface cracks) if filled correctly will only make a small deduction in value. Fractures will drastically reduce their price and cracked opals are not suitable for jewelry. Additional care needs to be taken if you intend to wear an opal on a daily basis.
Opals are generally untreated, but enhancements are often done to improve their appearance and durability. While there are a number of methods that are utilized to bring out their play-of-color, sugar and smoke treatment remain the most common.
Usually, white, gray or black opals are subjected to the sugar method, which involves immersing the gem in a sugar solution and then in strong sulfuric acid. This process makes the flashes of color more visible.
The smoke method also delivers the same result, but the process is different. Here the opal is wrapped in paper before being subjected to heat and smoke. This causes the particles of soot to penetrate the surface of the gem, giving it a darker background color and elevating the play-of-color.
Some of the other opal treatments include permeation with resin, wax, colorless oil resin, plastic, and hardeners. The opals available on our site are not enhanced in any way.
Quality & Grading
The color of an opal plays a significant role in determining its value. In the case of this particular gem, this factor represents the number and clarity of different hues present, along with the play-of-color.
The more commonly seen hues include blue and green, while warmer tones such as orange, pink, yellow and red are rare. If more warm colors are visible on the opal, then its price shoots up. The presence of pink is highly valued in an opal, but pure red is prized even more.
Saturation, hue and tone are the components that determine an opal’s clarity. For instance, a light blue or greenish-blue opal will not be as highly valued as a bright, pure blue.
Clarity of this gem is also influenced by the degree of transparency, along with the absence or lack of inclusions. The naturally occurring flaws in an opal include fractures, sand, chips and sandstone between the areas of color, among others. Their effect on value is proportional to their effect on the appearance of the gem. The more visible they are, the more they’ll bring down the value.
Opals, unlike other gemstones such as emeralds and sapphires, are not typically faceted. They are mostly cut into rounded cabochons and are set into a variety of jewelry, such as bracelets, earrings, rings, necklaces, pins and brooches. This gem is also used for carving small figurines, pretty curios and other decorative objects.
This gem occurs naturally in a variety of sizes, and is typically measured in carats. During the evaluation of an opal, it is given a price 'per carat'. The overall carat size of the stone will then influence its value.
Based on its various properties, an opal can be further distinguished into the following categories of quality:
Milky with a high play-of-color, only the top 1% of remarkable opal stones belong to this category. They are opaque and surface clean.
This category comprises of the top 10% of opal stones. They are milky and display medium play-of-color. The gems belonging to this category are opaque and have very slight surface blemishes.
Top 33% of the available opal stones fall in this category. Milky and opaque in appearance, they display a low play-of-color. These opals also have slight surface blemishes.
This category includes the top 75% of available opal stones that are milky with no play-of-color. They are opaque and have surface blemishes.
Opals are one of the most commonly worn gems; however, they are delicate and require special care. Varying amounts of water, present in its composition, can evaporate and cause the stone to lose its gleam or even crack. Keep the following tips in mind to maintain its beauty.
Extreme temperatures can harm an opal. It is essential to avoid hot or boiling water for cleaning. Also, care must be taken to keep it away from freezing cold.
A damp, soft cloth and mild cleanser can be used for cleaning. But harsh chemicals, bleach or abrasive agents must be strictly avoided as they can lead to scratches on the surface.
A soft bag made of cloth can be used for storing opals so as to maintain their shine and quality.
During regular wear, the skin’s moisture helps to keep the stone from drying out. So if you intend to store your opal jewelry for an extended period of time then seal it in a plastic bag with slightly dampened cotton wool. This is one of the ways you can help the stone retain its moisture.
Consider getting your jewelry examined by professional jewelers at least once in a year.
Opal is undeniably enchanting, and even William Shakespeare called it the "Queen of Gems" in his play "Twelfth Night”. Keeping in mind its various characteristics will help you recognize and appreciate the value of this charming gem.