Learn About Heat Treatments in Sapphires

What’s the Deal with Heat?

One of the most common sapphire treatments is heating. But what is it and how does it impact your sapphire? Which type of sapphire is better? Let’s dive in!

Most sapphires are heated to an extremely high temperature to intensify the color, remove color zoning and improve clarity. Sapphires have been heat treated for centuries - the earliest heat treatments involved packing the rough stones in clay and placing them in a fire which was then brought to a high temperature by using a blowpipe or a bellows to increase the flow of oxygen. Today, sapphires are placed in a furnace and heated to the desired temperature before being slowly cooled.

Is heat treatment bad?

The answer to that question is a resounding no! A very small percentage of the sapphires that are mined are of gem quality without being heated. Without this treatment, sapphires would be significantly less accessible for jewelry and we would be missing out on a lot of really beautiful gems!

Heat treated sapphires are still 100% natural sapphires. Heat treatments are an industry standard treatment that is permanent. Sapphires that are heat treated will not fade or change over time. Heated sapphires are not “lab” or “synthetic” in any way. To the naked, untrained eye, heated and unheated sapphires look exactly the same. A trained gemologist can generally tell if a sapphire shows signs of heat treatment by looking for specific characteristics within the stone at magnification. Gem laboratories can use specialized equipment to determine if a stone has been heated.

Are unheated sapphires better?

Well, that depends on your definition of “better”. Unheated sapphires are quite rare - and that means they are generally more valuable. These stones may exhibit more unique colors and inclusion patterns that you would not see in a heated stone because of the way the heat treatment changes the color or removes the natural inclusions. In that way, they are more unique.

Why would you choose a heated sapphire?

If you are looking for a stone with a vibrant, saturated color that is relatively free of inclusions and is a good value, a heat treated stone is the way to go.

Why would you choose an unheated sapphire?

If you are looking for a stone that has more natural qualities such as unique color, color zoning or silky inclusions, then look for an unheated sapphire. Unheated Montana sapphires are especially beautiful and one-of-a-kind. You might also consider an unheated sapphire if you are looking for a vibrant, high clarity stone that could be considered a collector’s item due to its rarity.

Are there other sapphire treatments?

There are a few other sapphire treatments that we do not recommend - among them lattice diffusion and Beryliuum treatments. These treatments introduce chemicals that artificially change the color of the stone. These treatments can be very shallow and are not permanent.

Let's sum it up!

The choice between unheated vs heated sapphires is really down to your personal preference and budget. At Stórica, we are committed to disclosing all known treatments and to helping you find the perfect sapphire for your jewelry!