There’s something almost magical about opal. One moment, it glows with fiery reds and deep blues, and the next, it flashes greens, yellows, or purples. It’s as if the gemstone is alive — constantly shifting with the light and the angle you view it from. But have you ever wondered why opal changes colour or what it means if your opal starts to look different over time?
In this guide, we’ll explore everything you need to know about opal stones, from why they have so many colours to what’s normal when it comes to colour changes. You’ll also learn how to protect your opal so it stays beautiful for years to come.
What Is Opal?
Opal is one of the world’s most fascinating gemstones. Scientifically speaking, it’s a hydrated form of silica, made up of tiny silica spheres packed together in a grid-like structure. Inside these spheres is water — typically between 3% and 21%, depending on the type of opal.
Unlike many other gemstones that form crystals (like quartz or diamond), opal is amorphous, meaning it doesn’t have a regular crystal structure. This is what gives it its unique visual properties — especially the famous play-of-colour that makes it shimmer in every hue imaginable.
Most of the world’s opal comes from Australia, which produces about 90% of all opal stones. Other significant sources include Ethiopia, Mexico, and Brazil, but Australian opals, especially those from Lightning Ridge, are often considered the best for their vibrant colour and stability.
Why Does Opal Have So Many Colours?
The rainbow-like flashes in opal, known as play-of-colour, aren’t caused by pigments or dyes — they’re purely a result of light diffraction.
Here’s how it works:
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The tiny silica spheres inside the opal act like a natural prism.
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When light enters the stone, it bends and splits into different wavelengths (colours).
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The size and arrangement of these spheres determine which colours you see.
Smaller spheres create blue and violet tones, while larger ones produce red and orange flashes — which are rarer and therefore more valuable.
It’s essentially nature’s own holographic display! That’s why no two opals are ever exactly the same. Every stone has its own colour pattern, its own personality.
Why Does Opal Change Colour?
Now that we know what causes opal’s colours, let’s look at why they sometimes change. There are a few key reasons why your opal might look different over time — and not all of them are bad.
1. Light and Angle
Opal’s colour changes depending on how light hits it. As you move the stone or change the viewing angle, different silica spheres reflect different wavelengths of light, creating a shifting colour effect. This is completely normal and one of the reasons opal is so captivating.
2. Moisture and Dehydration
Because opal contains water, it’s sensitive to changes in humidity and temperature. When an opal loses water, it can appear duller, cloudy, or even develop cracks (a process known as crazing).
According to data from the Gemological Institute of America (GIA), opals stored in very dry environments can lose up to 2% of their water content over time, which can slightly alter their appearance.
If your opal looks less vibrant or seems to have lost colour, it might be dehydrated. You can help restore some of its brilliance by storing it in a slightly humid environment or wrapping it in a damp cloth occasionally.
3. Exposure to Chemicals
Household cleaners, perfumes, and lotions can damage opal’s surface and cause colour fading. Because opal is relatively soft — only 5.5–6.5 on the Mohs hardness scale — it’s more sensitive than harder gems like sapphire or diamond.
Always remove opal jewellery before cleaning, swimming, or using harsh products.
4. Type of Opal
Some opals, like Ethiopian opals, are hydrophane, meaning they absorb water easily. When these stones get wet, they can temporarily change colour or become more transparent. Don’t worry — once they dry out, they usually return to normal.
Australian opals, on the other hand, are generally non-porous and more stable, so they rarely show these temporary changes.
Is It Bad If Opal Changes Colour?
Not necessarily! In most cases, colour changes are completely normal and part of opal’s charm. The shifting hues are a result of light interacting with the stone — a natural effect that makes opal so mesmerising.
However, if your opal becomes permanently dull, cloudy, or starts showing cracks, it could be a sign of dehydration or damage. In that case, it’s worth taking your stone to a professional jeweller or gemologist for assessment.
Proper care can prevent most issues. For example, keeping opals away from extreme heat, storing them separately from harder gemstones, and cleaning them gently with a damp cloth can make a big difference.
What to Do If Your Opal Changes Colour
If you notice your opal looking different, don’t panic. Here’s what you can do:
1. Check for Moisture Changes
If your opal has been exposed to very dry or very humid environments, the colour change might be moisture-related. Try keeping it in a sealed plastic bag with a damp cotton pad for a few days to rehydrate it gently.
2. Avoid Chemical Damage
If your opal jewellery has been in contact with perfumes, lotions, or cleaning agents, gently clean it with warm water and a soft cloth. Avoid using ultrasonic or steam cleaners — they can cause cracking.
3. Store Properly
Keep your opal jewellery in a fabric-lined box or pouch, away from other stones that might scratch it. Maintaining a bit of humidity helps prevent the stone from drying out.
4. Seek Professional Advice
If your opal shows cracks or permanent dullness, a jeweller may be able to repolish or stabilise it. Always choose someone experienced with opal, as it requires delicate handling.
Conclusion
Opal’s ability to change colour is exactly what makes it so special. It’s a living gemstone — dynamic, vibrant, and endlessly fascinating. Whether you’re admiring an Australian black opal or a fiery Ethiopian one, those flashes of light are part of what makes opal such a timeless treasure.
Most colour shifts are natural and harmless, but caring for your opal correctly ensures it stays stunning for decades. Keep it clean, protect it from heat and chemicals, and don’t let it dry out completely. Treat your opal with care, and it’ll reward you with a lifetime of beauty.
FAQs
1. Why does my opal look duller than before?
It could be slightly dehydrated. Try rehydrating it by storing it in a sealed bag with a damp cloth for a few days. Avoid exposure to extreme dryness or heat.
2. Can opal lose its colour permanently?
If exposed to chemicals or severe dehydration, yes, it can. But with proper care and storage, your opal should retain its colours for a lifetime.
3. Why does my opal look different in sunlight?
Opal’s play of colour reacts to different light sources. Sunlight often brings out reds and oranges, while indoor lighting may emphasise blues or greens.
4. Can I wear opal every day?
You can, but with care. Avoid wearing it during physical activities, cleaning, or swimming. Opal is softer than most gemstones and can be scratched or cracked easily.
5. Are colour changes a sign of a fake opal?
Not necessarily. Real opals naturally shift colours with light. However, synthetic opals may show overly uniform or repetitive patterns, which can be a giveaway.