Heated vs Unheated Sapphires

_{a heated and an unheated blue sapphires}

The heating of sapphires is an interesting subject. For it is one that is for the most part poorly understood. The heating of sapphires falls under the broader subject of the treatment of sapphires. The treatment of gemstones like sapphires is a complex and generally controversial matter. Since the types of gemstone treatments vary depending on the gemstone type (e.g. emeralds are generally not heat treated, but instead are subjected to oils and filler treatments). The problem with sapphire heating is often confused with the variety of practices used in gemstone treatment. Most of them are unethical and in some case are considered illegal, as they artificially altering the character of the gemstone, or seek to add different elements externally. The heating of sapphires is a distinct process that is an industry-accepted method of improving the natural qualities of the gemstone. Here you will learn about the features of this process, and why it is widely used and accepted practice. And how it relates to natural untreated sapphires.

Why are Sapphires Heated?

The heating of sapphires is an industry-accepted method for enhancing the natural qualities that already present in the gemstone. This is important to understand. Since the heating of sapphires is a method that is applied to natural sapphires, and not the lab-grown artificial variants; it is important to not confuse heated sapphires with synthetic ones. Heating sapphires is done to improve the existing qualities of the gemstone. So the effectiveness of the heating process comes partly comes down to the quality of the corundum stone. And the heating of the sapphires, as we shall explain, does not involve the addition of other materials. The heating of the stone is a process of enhancement, not addition. With the main focus being its colour. If you know anything about sapphires, colour is arguably the most significant factor when it comes to determining sapphire value. So how does heating a sapphire affect its colour?

_{Un-heated sapphires are very rare}

As the reader can see in the pie chart the prevalence of natural unheated sapphires is a rarity in the market. So getting hold of them is naturally a challenge, and gem companies and merchants who trade in these type of sapphires will naturally add a considerable mark-up to the final price of the gemstone. Since heating of sapphires is a process that is done to enhance the natural qualities of the sapphire; sapphires that are found in a natural (unheated) state containing those desired attributes are even more of a rarity. So getting them will not only prove to be a challenge but will also require a huge payout. Of course, the enthusiast who wishes to get a hold of a natural, unheated and top quality sapphire that also scores highly in colour, carat, cut and clarity can do so. But is it worth the effort and cost?

What does Heating do to a Sapphire?

When it comes to the colour that is present in sapphires, it is important to note that the colour that is present in it is the result of external elements, which exist as impurities. And the presence of trace elements such as titanium and iron, that are found at various levels, in various parts of the gemstone. Hence the dispersion of colour within the gemstone is not uniform, and at times could be concentrated in a particular area. This is not always desirable. And from the standpoint of optimising the colour in sapphires, heating is a process that helps improve the dispersion of colour within the gemstone. At the same time the heating, which the entire gemstone is subjected to, helps to establish a degree of uniformity colour in the gemstone. However, this is only the surface of the effects of the sapphire heating process. The actual interactions that take place during this course of interaction are quite complex, but a general overview of these interactions is helpful. Here’s a list of changes that takes place to the corundum:

Heating causes the rutile needles (traces of titanium oxide), which contributes to the asterism or star shape, in the sapphire to loosen. Which can increase or decrease this particular effect. The effectiveness of this factor comes down to the existing quality of the stone
Sapphires, like other gemstones, often come with a number of inclusions. With higher quality sapphire tending to have fewer and/or smaller ones. The heating of the sapphires helps to fuse the inclusions in the sapphire. Which potentially reduce their unfavourable effects on the colour and clarity of the stone.
Helps alleviate colour zoning. As noted colour in sapphires is not always uniformly present in the gemstone. The heating of the sapphire can help disperse colour to other parts of the gemstone, to help provide a clearer look. However, this process must be handled carefully, for poorly heated stones can leave colour stains that look unnatural. This brings us to the actual process of how these heat treatments are carried out.

How are Sapphires Heated

Sapphires are heated using dedicated ovens which heat the gemstones for a certain duration. The temperatures that sapphires vary, with temperatures ranging from 1000 ⁰C to 1800 ⁰C. The nature of the heating can vary from company to company and region to region. In top gem producing nations like Ceylon, traditional heating processes are used. Where gas furnaces involve a great deal of manual involvement and observation. To the more advanced electrical burners, or at times even a combination of the two. The right temperature and the duration to which the gemstone is burned comes down to the character of the sapphire, the expectations of the jeweller and their level of expertise. In addition, there is also the cultural dimension. Heating sapphires is a part of a wider process going from the sapphire from mines to the jewellery store. Hence there is a close integration between these processes.

_{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, and of demand and supply measures the above graph may look familiar. Besides outlining the obvious correlation between the increase in size, colour (improvement) clarity of the gemstone and a broader increase in its value and hence price. Notice the interesting relationship between the heating of a sapphire and the increase in its market value. Contrary to what many may think, the heating of sapphire is a process that enhances the natural characteristics already present in the sapphire. Hence by doing so the value of the gemstone also increases accordingly. What is interesting however is that the value addition that the gemstone gains by heating steadily increases the value of the sapphire, depending on the natural qualities that it already possesses. Which at a certain point begins to surpass the quality and value of the unheated stone. As the graph shows, whilst controlling for other sapphire qualities, beyond a certain point the value of the heated sapphire increases considerably over the unheated stone.

The Acceptability of the Heating Process: A Value Proposition

Sapphire heating is an interesting but controversial subject. Especially so, as certain jewellers and gem companies have begun to market themselves as those that specialise in natural “unheated” or “untreated” sapphires. It is important to note that sapphire that is heated, do not necessarily fall under the category of “treatment”. Which, as we explained, involves many unethical processes. The fundamental reasons why sapphires are heated is because over 95 per cent of sapphires that are found in nature do not exhibit the qualities expected in a top-quality sapphire. Sapphires, like any resource that is taken from nature, often is not found in an ideal state. There is always a process of improvement, a refinement that the mineral for instance is subjected to. The same principle applies when it comes to sapphires. The natural state in which sapphires are found in nature is not suitable for fine jewellery making. This applies even to unheated sapphires. Since all sapphires need to be cut, shaped and polished and prepared to be set in fine jewellery.

If the reader is uncertain about heated and unheated sapphires, and why companies resort to this process. Think of it this way: what matters is the quality of the final product. If what you value is a top-quality engagement ring, with optimal colour, great clarity, and awesome: a gemstone whose rich qualities will last a long time, what ought to matter is the value of the final product to contain these attributes. At Brilliyond our primary focus is to bring the best quality sapphires to those who value beauty and value. A goal to which we do everything we can to achieve.