Heated or natural gemstone: what is the difference in value?

What if the beauty of a precious stone was not enough to determine its price?

Behind the perfect brilliance of a ruby ​​or the limpidity of a sapphire sometimes lies a heat treatment. A common but little-known practice, heating precious stones can significantly influence their value. So, natural or heated stone: how can you tell the difference, and above all, which should you choose for an investment or a prestigious piece of jewelry?

1. What is a heated gemstone?

In the world of gemology, heating is a process used to enhance the color and clarity of a gemstone . It is a heat treatment, applied at very high temperatures, primarily to stones such as sapphire, ruby, or topaz.

This treatment, although common and often accepted in the market, alters the natural properties of the gemstone . It is not visible to the naked eye, which makes certificates of authenticity essential to distinguish treated stones from natural ones.

💡 According to the GIA, more than 95% of rubies on the market are heated to improve their color.

2. Why are the stones heated?

Stones extracted from the earth do not always have the expected appearance: some are too dark, others too light or cloudy. Heating allows for a more vibrant color and a more appealing transparency, meeting the aesthetic criteria sought by buyers.

But this treatment diminishes the stone's rarity , because it is reproducible and widespread. That's where the difference in value lies.

🔎 Want to learn more about gem evaluation criteria? Check out our article on how to be sure of a gemstone's true value .

3. What is the difference in value between natural and heated stone?

It's simple: rarity dictates the price . A natural, unheated gemstone is considered rarer, and therefore more valuable. At equal quality, it can cost two to five times more than a heated stone.

For example :

• A natural 2-carat sapphire , of a deep blue, can be worth more than €10,000.

• The same heated sapphire , with a similar appearance, will be traded for around €3,000 to €4,000.

These price differences are explained by the exceptional nature of untreated stones. They are also more sought after by collectors and investors.

4. How can you tell if a stone has been heated?

Impossible to detect without specialized tools. That's why it's essential to:

• Request a certificate of authenticity issued by a recognized laboratory (GIA, LFG, SSEF…),

• Buy from trusted professionals ,

• Seek guidance from a gemology expert.

💎 To go further, discover how to assess the quality of a diamond , another precious stone whose value varies according to strict criteria.

5. Which option to choose: heated or natural?

It all depends on your goals. Are you looking for an elegant piece of jewelry at an affordable price? A heat-treated stone can be an excellent choice, as long as the treatment is transparent and declared.

However, if you are considering a long-term investment or future resale, opt for certified natural stone. It's a rare, authentic investment and potentially more profitable in the long run.

💡 High-quality natural stones represent less than 1% of the global market.

🔗 Want to invest wisely in gems? Check out our ranking of the stones to invest in in 2025 .

Conclusion: Whether natural or heated, authenticity makes all the difference

Beyond appearance, transparency regarding a stone's treatments is a sign of trust . A heated stone may have a magnificent luster, but only the authentic nature of a gem guarantees its rarity… and its value.

Do you have any doubts about a stone you own? Come see us in store, we will be happy to advise you and help you identify its origin and potential.