Heated vs Unheated Sapphires

_{a heated and an unheated blue sapphires}

The heating of sapphires is a fascinating topic, though often poorly understood. It falls within the broader category of gemstone treatment, a complex and sometimes controversial subject.

Sapphire heating is frequently misunderstood and mistakenly associated with unethical gemstone treatment practices. These questionable methods often involve artificial alterations or the addition of external elements, which can sometimes be illegal.

In contrast, the heating of sapphires is a distinct, industry-accepted process designed to enhance the stone's natural qualities. This guide will explore the features of sapphire heating, explain its widespread acceptance, and clarify its relationship to natural, untreated sapphires.

Why are Sapphires Heated?

The heating of sapphires is a widely accepted industry practice aimed at enhancing the natural qualities already present in the gemstone. It's essential to understand that this process is applied exclusively to natural sapphires and should not be confused with synthetic, lab-grown variants.

Heating improves the inherent features of the sapphire, with the quality of the corundum stone itself playing a significant role in the effectiveness of the process. Importantly, sapphire heating does not involve the addition of any foreign materials. It is strictly a process of enhancement, not alteration, with the primary focus on improving the gemstone’s colour.

When sapphires are mined from the earth, they are all in an unheated state. The decision to heat or leave a sapphire unheated depends on the potential value that can be added through heating versus the value of preserving its natural, untreated state.

If the enhancement of colour and clarity achieved through heating adds more value than the premium associated with it remaining unheated, the sapphire is typically heated. Conversely, if retaining the unheated state results in a higher overall value—even accounting for the lack of enhancement—the gemstone is kept unheated. This careful assessment ensures that the sapphire's natural qualities are optimally leveraged to achieve the greatest value.

Colour is arguably the most critical factor in determining the value of a sapphire. But how exactly does the heating process affect a sapphire's colour? Let’s explore this further.

_{Un-heated sapphires are very rare}

As shown in the pie chart, natural unheated sapphires are exceedingly rare in the market. Acquiring one is a significant challenge, and gemstone companies and merchants who specialise in these sapphires often apply a considerable mark-up to their prices.

Since the heating process enhances the natural qualities of sapphires, finding an unheated sapphire that naturally possesses those desired attributes is even rarer. This makes obtaining such gems not only difficult but also highly expensive.

For enthusiasts seeking a natural, unheated sapphire of exceptional quality—one that excels in colour, carat, cut, and clarity—it is possible to find these treasures. However, the question remains: is the effort and substantial cost truly worth it?

What does Heating do to a Sapphire?

The colour in sapphires is primarily the result of trace elements, such as titanium and iron, which exist as impurities within the gemstone. These elements are present at varying levels in different parts of the stone, leading to uneven colour distribution. In some cases, this concentrated dispersion of colour may not be desirable.

To address this, the heating process plays a vital role in enhancing the gemstone's appearance. By subjecting the entire sapphire to heat, the process improves the dispersion of colour, creating a more uniform and visually appealing result. While this surface-level explanation highlights the primary purpose of sapphire heating, the interactions that occur during the process are complex and nuanced.

Here is a general overview of the changes that occur to the corundum during heating:

Oxidation and Reduction Reactions
- The heating process alters the oxidation state of trace elements, such as iron and titanium, which directly affects the sapphire's colour. For example, changes in the valence state of these elements can intensify or modify the hue.
Improved Colour Dispersion
- Heat causes the trace elements to redistribute more evenly throughout the gemstone, reducing undesirable colour concentration in specific areas.
Removal of Unwanted Colour Tones
- Heating can reduce or eliminate undesired secondary hues, such as greenish or brownish tints, resulting in a purer and more vibrant primary colour.
Clarity Enhancement
- Inclusions or internal flaws may be partially dissolved or restructured during heating, improving the gemstone's transparency and overall appearance.
Creation of Rutile Needles (in some cases)
- Heating at specific conditions can help create or refine rutile needles, which are responsible for phenomena like asterism (star effects) in star sapphires.
Stabilisation of the Crystal Lattice
- Heat treatment can stabilise the internal structure of the gemstone, ensuring a more durable and aesthetically consistent product.

These processes collectively enhance the colour, clarity, and overall beauty of sapphires, making heating an essential and widely accepted practice in the gemstone industry.

How Sapphires are Heated

Sapphires are heated using specialised ovens designed to treat gemstones over a specific duration. The temperatures used in this process typically range between 1000°C and 1800°C, depending on the nature of the sapphire and the desired outcome. The heating methods can vary significantly across companies and regions, reflecting differences in tradition, technology, and expertise.

In leading gem-producing nations like Sri Lanka (formerly known as Ceylon), traditional heating methods are still widely practised. Gas furnaces, which require a high level of manual involvement and careful observation, are often used. However, more advanced techniques, such as electric furnaces, or even a combination of traditional and modern methods, are also employed.

The choice of temperature and heating duration depends on several factors, including the unique characteristics of the sapphire, the jeweller’s requirements, and the expertise of the heating specialists. There is also a cultural dimension to consider, as the heating process is closely integrated into the broader journey of the sapphire—from the mine to the jewellery store. This integration highlights the deep connection between the craftsmanship of sapphire heating and the gemstone’s ultimate transformation into a finished piece of jewellery.

_{how heated vs un-heated affects the quality and the price of sapphires}

_{For the same price, you can get a bigger and beautiful heated sapphire and if you are looking for a specific quality you can get an un-heated one for a cheaper price}

For students of economics familiar with demand and supply dynamics, the graph above may appear intuitive. It illustrates the correlation between factors like the size, colour quality, and clarity of a gemstone with its value and price. However, what stands out is the relationship between the heating of a sapphire and its market value.

Contrary to popular belief, heating a sapphire does not diminish its worth. Instead, it enhances the gemstone’s natural characteristics, thereby increasing its value. Interestingly, the extent of this value addition depends on the sapphire's inherent qualities. As the heating process improves the gemstone’s colour and clarity, its market value rises.

With a given budget, you can acquire a significantly higher-quality heated sapphire in terms of colour, size, and clarity compared to an unheated sapphire. Additionally, if you are seeking a specific combination of colour, size, and clarity, a heated sapphire offers an excellent option at a much more affordable price point.

What matters the most

Sapphire heating is a fascinating yet often misunderstood topic. It’s important to understand that heated sapphires don’t necessarily fall into the category of "treated" gemstones, a term often associated with unethical or artificial enhancement methods.

The primary reason sapphires are heated is that over 95% of naturally occurring sapphires lack the qualities required for top-tier gemstones. Like any natural resource, sapphires are rarely found in a state suitable for fine jewellery. Refinement processes, including cutting, shaping, and polishing, are necessary for all sapphires—even unheated ones—to prepare them for jewellery making. Heating is simply an additional step to enhance the gemstone’s natural beauty, improving its colour and clarity to meet the standards of high-quality jewellery.

At the end of the day what truly matters is the quality of the final product. If your goal is a stunning engagement ring with optimal colour, exceptional clarity, and enduring beauty, the focus should be on the attributes of the finished gemstone, rather than whether it was heated.

At Brilliyond, our mission is to deliver the finest quality sapphires to those who value both beauty and long-term worth. We are dedicated to achieving this goal by offering gemstones that meet the highest standards of craftsmanship and excellence.