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Heated vs Unheated Gemstones: The Truth Jewellers Don’t Want You to Know

Posted on September 8th, 2025 05:28 PM

Most people consider the color, clarity and carat when purchasing gemstones. However, there is one aspect that goes unnoticed most of the time, and that is whether the gemstone is heated or not. That is a fact, which can have a tremendous impact on the value, rarity and even authenticity of the stone. And this is the kicker - most jewelers will not tell you unless you inquire.

What then is the real difference between heated and non-heated gemstones? Why does it matter? And which one should you select? We shall get into the glittering world of gemstone treatments and unravel the truth that has been staring us in the face.

Let's start with what does it mean when a gemstone is heated?

What does “Heated” mean in Gemstones?

One of the most popular treatments used in the gemstone industry is heating. It is the art of exposing a stone to heat in order to improve its colour and clarity. You can imagine it like a cosmetic makeover, taking away the flaws and deepening the colour to make the gem more aesthetic.

This is particularly typical to do in the corundum mineral family, which includes ruby stone and sapphires. Citrine, aquamarine and tanzanite stone are also common stones that are heated.

A heated gem might appear to the naked eye as immaculate, rich, and crystal clear. However, that perfection comes with a cost; well, it decreases the cost of the gem, since it is not absolutely natural.

Blue Sapphire - 4.06 Carat

Burma Natural Ruby - 3.01 Carat

Emerald Ethiopia - 8.70 Carat

Yellow Sapphire - 11.05 Carat

What Are Unheated Gemstones?

Unheated gemstones are simply what they mean: stones that have not been subjected to artificial heat. They are in the purest form and are as they were discovered in nature. These stones can contain some inclusions, uneven colour, or minor flaws, but that is what makes them so attractive.

Stones that are not heat-altered are extremely rare. Actually, of the sapphires mined, only about 1 out of 100 is of good quality and without heat treatment. The scarcity makes them very popular among collectors and connoisseurs.

Check It out - Type of Treatment Used on Rubies and Sapphires

Value & Rarity: Heated Vs Unheated Gemstones

And here is where it becomes interesting. Common and more affordable are the heated gemstones, but unheated gemstones are higher priced. They are more valuable when they are not touched by anyone and when they have good color and clarity without any enhancement.

It is common to find unheated stones with a certification to confirm that they are natural. This lab report is important since it demonstrates that the gem has not been tampered with, which can greatly influence the resale price and the possibility of investment.

Can You Spot the Difference?

Visually? No. Even an expert person would not be able to distinguish between the heated and unheated gemstones. This is why it is so important that sellers are transparent. Qualified jewelers will tell you whether a stone has been treated and will give you certification when it is unheated.

A sapphire stone doesn’t need a specific label to be unheated, so you can be certain that it has undergone treatment. It is a business, not a trick--but it is something the consumer ought to know.

Ethical & Environmental Considerations - Unheated vs Heated Gems

Of course, there is the ethical side of it. The heating of gemstones gives jewelers the ability to utilise stones that would have been thrown away. This minimises waste and utilises additional parts of the natural resources on earth. To that extent, heat treatment could be regarded as a sustainable practice.

But, when you are a person who appreciates natural, raw beauty and likes to possess a stone that is one in a row, you can use unheated gemstones. Their inclusions and imperfections are as unique as fingerprints--they cannot be replicated.

Are Heated Or Unheated Gems Better For Astrology?

For astrological use, you have to go for a natural gemstone, an unheated one, whether it's a Navratan or its Upratan.

According to the expert astrologers, one should wear natural gems. Unheated Navratan only to get the blessings of an astrological planet. Only natural gems will align with the energies and bring the wearer its powers.

Which Should You Choose - Heated or Non-Heated Gemstone?

It depends on your priorities:

Preference	Best Choice	Why
Budget-friendly beauty	Heated gemstones	More vibrant, affordable, widely available
Rarity & investment	Unheated gemstones	Natural, rare, higher resale value
Ethical sourcing	Heated gemstones	Reduces waste, uses more mined material
Unique character	Unheated gemstones	Natural inclusions, one-of-a-kind charm
Astrological Purposes	Heated Gemstones	Believe is that only natural gems bring you energies

More to read - Gemstone Meanings & Powers: Significance of 25 Most Popular Gems

Final Thoughts

The gemstone world is glittering--but it is subtle as well. Treated vs untreated and heated vs unheated is not a mere technicality it is a measure of the degree to which you appreciate authenticity, rarity and transparency.

Next time you go out to get a gem, ask the correct questions. Request certification. And above all, pick a stone that appeals to your values.

When you find out the backstory behind your stone, that is what is really sparkling.

Want natural gemstones with certification - visit Navratan, the online gem bazaar, a reputable seller with an exclusive collection of original and authentic gemstones.