As enchanting as they are enigmatic, opals have captivated gemstone enthusiasts for centuries with their vibrant interplay of colors and their extraordinary beauty. This dazzling array of hues is not always constant, however. Often, owners of these gemstones find themselves asking the question, “Why do my opals turn yellow?”
Opals, unlike many other gemstones, are hydrated silica, which makes them exceptionally unique but also peculiarly sensitive to their environment. This can sometimes result in a change of color over time, turning an initially brilliant stone a disheartening shade of yellow. The phenomenon might seem alarming to some, or even disappointing to those who appreciate the opal’s normally dazzling multicolor effect. But fear not—this color alteration can frequently be understood, managed, and even prevented.
In this blog post, we will illuminate the factors that lead to your precious opal turning yellow, delving into the science behind this enigmatic color shift. Additionally, we’ll share essential tips on opal care to prevent discoloration, helping to ensure that your gemstone retains its vibrant, captivating allure for generations to come. Whether you’re an opal owner concerned about your gem’s changing tones or a potential buyer wanting to learn more about this delicate gemstone’s maintenance, this comprehensive guide has got you covered.
Stay tuned as we unravel the fascinating world of opals, explore their interaction with their surroundings, and provide essential advice to keep your opal as captivating as the day you first held it in your hands.
Reasons Why Opals Turn Yellow
Moisture
Opals are often referred to as “living stones” because they contain water—typically between 3% and 21% of their weight. This water content plays a significant role in an opal’s characteristic iridescence, but it can also make the gem vulnerable to changes in its environment, particularly when it comes to moisture levels.
The yellowing of opals due to moisture (or lack thereof) usually has to do with the dehydration process. When opals lose water, they can begin to dry out, leading to a change in color. This dehydration can occur when an opal is exposed to extreme heat, low humidity, or even stored improperly over a long period of time. As the water evaporates from the opal’s internal structure, the stone may start to exhibit a yellow, brown, or in more extreme cases, a “crazed” appearance with a network of fine cracks.
The change in color is essentially a result of the way light interacts with the microscopic silica spheres that make up the internal structure of the opal. As the stone loses water, these spheres may shift, changing the wavelengths of light they reflect, which in turn alters the perceived colour of the opal.
It’s also worth noting that this process is usually gradual, meaning an opal won’t turn yellow overnight due to dehydration. But over time, a lack of proper care can lead to noticeable discoloration.
Understanding this, it’s important to know how to properly care for your opals to maintain their water content and prevent them from turning yellow. Measures such as storing your opal in a sealed bag with a damp piece of cotton or cloth can help maintain its moisture level. Moreover, avoiding exposure to heat or dry environments, as well as sudden temperature changes, can help preserve the opal’s natural color and vibrancy.
Absorption Of Liquids
As previously mentioned, opals are unique among gemstones due to their water content, which gives them their fascinating play of colour but also makes them highly porous. This porosity means they can absorb liquids relatively easily, which can cause them to change colour depending on the nature of the absorbed substance.
If an opal comes into contact with a colored or staining liquid, such as coffee, wine, or even certain oils, it can absorb the liquid and cause a change in the stone’s appearance. In many cases, this can lead to a yellow or brownish hue, essentially “staining” the opal.
This discoloration happens because the absorbed liquid changes the opal’s internal structure, affecting the way light is refracted and reflected within the stone, thus altering its perceived colour.
For this reason, it’s important to be mindful of where you’re wearing your opal jewelry. It’s generally recommended to avoid wearing opal rings while cooking, cleaning, or doing anything that might expose the stone to potentially staining substances.
When it comes to cleaning your opals, it’s best to stick with mild soap and water, and avoid harsh chemicals or cleaners. And if your opal does become stained, it’s usually best to consult with a professional gemmologist or jeweller, as they may be able to assist in restoring the stone’s original colour.
Remember, part of the allure of owning an opal is its unique characteristics, and taking care of your precious stone should always involve being mindful of its distinctive, porous nature.
Loss Of Water
Opals are hydrous silica minerals, meaning they have a significant water content—anywhere between 3% and 21% by weight. This water is actually part of the gemstone’s internal structure, with molecules of H2O interspersed among the silica spheres that give opals their unique play-of-color.
Over time, however, opals can lose their water content. This can occur when they’re exposed to high temperatures, low humidity, or simply left in an environment that causes them to dry out. This process is known as dehydration.
When an opal dehydrates, the loss of water can cause the internal structure of the opal to shrink and change. This alteration impacts how light is refracted and reflected within the stone, and it can cause the gem’s color to shift. In many cases, this leads to a yellow or brownish hue. Severe dehydration can even cause an opal to develop a network of fine cracks, a phenomenon known as “crazing.”
Dehydration isn’t an immediate process, and an opal won’t turn yellow overnight. However, if left in a dry environment for an extended period of time, it may gradually lose enough water to cause noticeable color changes.
This is why it’s so important to properly care for and store your opals. Keeping them in a moist environment can help maintain their water content and prevent discoloration. Some people store their opals with a small, damp piece of cotton or cloth to keep the humidity levels high. It’s also important to avoid sudden temperature changes, which can cause the water in an opal to evaporate more quickly. Proper care can ensure your opals maintain their brilliant colour and vibrancy for years to come.
Can An Opal Be Restored From Yellow Colour Back To Normal?
Yes, it is possible to restore the color of a yellowed opal in some circumstances, but it largely depends on the reason behind the discoloration.
If the opal has turned yellow due to dehydration, it may regain some or all of its original color once rehydrated. To rehydrate a dehydrated opal, it can be placed in a container with water, or a water and glycerin solution, where it can slowly absorb moisture back into its structure. This process can take from a few days to several weeks or even months, depending on the severity of the dehydration. It’s important to note that this should be done with caution, as rapid rehydration can cause damage.
If the yellowing is due to absorption of a staining substance, the stone can potentially be cleaned to remove the discoloration. Mild soap and water are typically recommended for cleaning opals, but if this doesn’t work, a professional jeweler or gemologist may be able to help. They might use a special cleaning solution or a more involved treatment process.
However, if the yellowing is due to changes within the stone’s structure, such as aging or exposure to certain environmental conditions over a long period of time, it may not be possible to fully restore the opal’s original colour.
In all cases, if you’re unsure about how to restore the colour of your opal, it’s best to consult with a professional to avoid causing further damage to the stone.
For further information on restoring opals, you can visit sources such as the Gem Society’s guide on opal care
How To Care For A Opal From The Beginning:
Owning an opal can be a delightful experience given its unique allure, but this precious gemstone does require a bit of special care. Here are some tips on how to care for your opal from the very beginning:
Protect from Hard Knocks and Scratches: Opals are relatively soft gemstones (rating between 5.5-6.5 on the Mohs hardness scale), making them susceptible to scratches and damage from impacts. If you own opal jewelry, it’s best to remove it before participating in any physical activities that could lead to hard knocks.
Avoid Extreme Temperatures: Extreme heat and cold can be detrimental to opals due to their water content. High temperatures can cause the water within an opal to evaporate, leading to cracking or “crazing.” On the other hand, extreme cold can cause the stone to fracture. Always protect your opals from extreme temperature fluctuations.
Maintain Moisture: Because opals contain water, they can dry out and become discolored over time. To prevent this, you can store them in a sealed bag with a small, damp piece of cotton or cloth. This can help maintain an opal’s water content and prevent discoloration.
Avoid Chemicals: Opals can absorb liquids, making them vulnerable to damage from chemicals found in cleaning products, cosmetics, and even certain types of water. Always remove your opal jewelry before cleaning, bathing, or swimming. It’s also best to avoid using ultrasonic jewelry cleaners, as the vibrations can cause damage.
Clean with Care: When your opal needs cleaning, use mild soap and warm water. Avoid harsh chemicals or scrubbing, which can damage the stone. Simply wipe the opal gently with a soft, damp cloth.
Store Properly: Store opals separately from other jewelry, as they can easily be scratched. A soft cloth bag or a fabric-lined jewelry box can be a good choice.
Regularly Inspect Your Opals: Particularly for opal jewelry, regular inspection can help identify any potential issues, like loose settings or signs of damage, before they become serious.
Seek Professional Help When Needed: If your opal becomes damaged or discolored, it’s best to seek help from a professional jeweler or gemologist. They can often provide advice or perform necessary repairs.
Caring for an opal may require a little effort, but the reward is a beautiful, vibrant gemstone that can be enjoyed for generations. By taking these precautions, you can ensure your opal stays as dazzling as the day you got it.
