Heated or unheated sapphire?

Unheated sapphire can naturally be used in jewelry, but heated sapphire is not considered "denatured". Here's an update on this age-old technique, its advantages and why some prefer to avoid it.

What is a heated sapphire?

Heating sapphire is an extremely common process, carried out either in a high-temperature furnace (up to around 1,800°C) or in the traditional way. It has been done since ancient times.

The aim is to improve natural imperfections, inclusions and lack of color intensity or homogeneity. Many blue sapphires are naturally of insufficient quality to be used in jewelry, being alternately too light or too dark. That said, these gems come in a variety of colors, and many can be heated, such as purple sapphire. The result is better saturation.

The vast majority of sapphires are heated, regardless of their origin in the world.

How much does unheated sapphire cost?

Theoretically, unheated blue sapphire is more expensive than heated sapphire. The same applies to other colors. Unheated sapphires are rarer, and their value increases. Some stones are even rarer, such as unheated Burmese sapphire, with its remarkable purity and brilliance. The same goes for unheated Ceylon sapphire, which, although less rare, is also renowned for its high quality and diversity of shades.

However, the price of a sapphire does not depend solely on its heating. The price of a high-quality heated sapphire may well be higher than that of a less exceptional unheated sapphire.

Is it acceptable to heat sapphire?

Whether or not additives are used (diffusion treatment), sapphire heating is a totally accepted practice in the world of jewelry. It is specified on gemmological certificates and considered normal, even essential, for many stones, including diamonds and prestigious Burmese rubies. Among gemstones, only emeralds cannot be heated.

Heated or unheated sapphire: which to choose?

Buying an unheated sapphire can have its advantages, provided the stone is naturally of good quality, of course. Lovers of authenticity prefer sapphires that have not been embellished, seek out rarer stones or collect stones of greater value. For the creation of rings and jewelry, many people turn to heated sapphires because of the price or simply because they are easier to find, in a variety of shapes and colors. An unheated sapphire ring can require a great deal of research.

Can you recognize a heated sapphire?

A gemmologist has the necessary equipment to recognize a heated sapphire from an unheated one. With the naked eye, this is impossible. On the other hand, take a pink sapphire, for example, which is tending towards brown: you can clearly see the difference after heating.

Heating does not denature a sapphire

Heating is not considered a treatment per se. That's why a heated sapphire is no less valuable than an unheated one. Treatments that can significantly alter the nature of the stones are more controversial. But if they are mentioned on the certificate of authenticity (as French law requires), there is no deception. A good example is the treatment known as filling, which consists of injecting products into the fractures of a stone, with the aim of making it more beautiful and solid. This treatment improves appearance, but impacts physical properties.