Heat-Treated vs. Unheated Sapphires—Does It Really Matter?

I get this question all the time: “Should I buy a heat-treated sapphire, or is an unheated one better?” The answer? It depends on what you’re looking for.

Heat treatment is one of the most common enhancements in sapphires, and it’s not a bad thing—in fact, about 90% of sapphires on the market have been heat-treated to improve their color and clarity. But for collectors, connoisseurs, and investors, unheated sapphires are the real prize.

Let’s break it down.

What Is Heat Treatment in Sapphires?

Heat treatment is a process where a sapphire is heated at extremely high temperatures (around 1,700-1,900°C) to:

✔ Enhance color, making it richer and more vibrant

✔ Reduce visible inclusions, improving clarity

✔ Make the sapphire more visually appealing overall

It’s a completely permanent treatment—meaning the results won’t fade or change over time. And here’s the key: heat treatment doesn’t make a sapphire synthetic or “fake”—it simply enhances the natural qualities of the stone.

But some people prefer sapphires that are 100% natural, untouched by any enhancement. That’s where unheated sapphires come in.

Why Unheated Sapphires Are More Valuable

Think about it like this: if you could find a sapphire with amazing natural color and clarity—without needing any enhancements—it’s significantly rarer than a heat-treated one. Rarity drives value.

💎 Unheated sapphires are usually priced 30-50% higher than comparable heated ones.

💎 They are harder to find, making them more desirable for collectors and investors.

💎 Certification matters. Always get an official lab report (GIA, GRS, or AGL) to confirm whether a sapphire is unheated.

Some of the world’s most famous and expensive sapphires, like the Blue Belle of Asia (392.52 carats), are unheated—further proof that collectors place a premium on untreated gems.

Investment Value: Heated vs. Unheated Over Time

Over the past 10 years, the price of unheated sapphires has steadily increased due to rising demand and limited supply. While heated sapphires remain affordable and accessible, unheated stones have outpaced them in long-term appreciation.

Here’s a simple comparison:

📈 A 3-carat heated sapphire that sold for $5,000 a decade ago might now be worth $6,500-$7,000.

📈 A 3-carat unheated sapphire that sold for $10,000 a decade ago could now be worth $18,000-$20,000.

For those thinking about long-term value and rarity, unheated sapphires are the way to go.

So, Which One Should You Buy?

If you’re buying a sapphire for jewelry and everyday wear, a well-cut, heat-treated sapphire is a fantastic option that offers exceptional beauty at a better price.

But if you’re looking for an investment piece, a collector’s gem, or something truly rare, go for an unheated sapphire—just be ready to pay a premium.

I personally curate both heated and unheated sapphires, always ensuring top quality. Check out some of my best pieces here:

💎 Certified 2.45ct Unheated Royal Blue Sapphire Ring

💎 Certified 1.80ct Heated Blue Sapphire Cushion Cut Ring

Want help picking the right one? Let’s talk!

📞 Call or text me at (212) 921-4647

🌍 Visit www.nektanewyork.com