The difference between sapphire burning and non-burning, the value and function of heat treatment

When we buy gems, we often hear that sapphires are burned and non-burned. What does the two mean? What is the difference? If we want to buy gems, do we buy burned or non-burned? These questions often accompany us.

First of all, we must know that in most cases, non-burnt gems are rarely used as ornaments. Generally, gems from raw stones to bare stones need to go through other processes in addition to cutting, so as to change the color, transparency, and glint of gems

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Why burn gems and what does heating do?

The purpose of heating is to make the gemstone color look better (improve the uniform color division, brighten and darken), and at the same time improve the transparency of the gemstone.

Most of the better-looking sapphires we see in the market are treated in this way.

We use the following intuitive pictures to explain what effect heating treatment can produce in color, but not all heated gems will look good. Heating treatment is a more complicated and experience-intensive job.

In the heat treatment, the gemstone needs to be heated above 1200 ° C. The heating will change some mineral elements in the gemstone, and these minerals will affect the color of the gemstone. For example, an overly dark sapphire can be heated at a temperature of 1,000 to 1600 degrees Celsius for about a day to oxidize and reduce the iron content present, thus brightening the tone of the gemstone.

Of course, not every gem here can be turned into a beautiful color by heating, and there must be failures.

On the other hand, heating can dissolve the inclusions in the gemstone, thus improving the transparency of the gemstone.

The mark on the certificate

For Sky Burning Baby that has not been heated, the general identification certificate is marked: "no indications of heating" or "NH."

Take GRS as an example. If it is a gem without burning, the certificate will be marked:

Gems without heat treatment

H is heat treatment, while GRS is graded according to heating residues, Be shows an increase by adding elements such as beryllium

Gems have burnt and non-burnt value

Thinning is the most important thing, and only about 1 to 2% of the gems in circulation on the market are unburned.

Obviously, if sapphires without thermal processing are rarer than heated sapphires, the price will be higher.

And with the passage of time, the price of unburned sapphire will be higher.

Many businesses here also have a new burn and old burn saying. Old burn is a traditional heating treatment, optimized for heating. New burn is through chemical elements, such as adding beryllium, if it is new, the value of the gemstone will be greatly discounted.

Does it give priority to buying unburned gems?

Since the value of unburnt gems is higher than that of burnt gems, does that mean that buying sapphires gives priority to buying unburnt gems? The answer is not necessarily.

As I said earlier, burning is to improve the color and transparency of the gemstone. The optimized gemstone will look better and be more suitable for making various ornaments. If you buy and wear it yourself, you should buy it from an aesthetic point of view.

Although the value of unburnt gems was high, because they had not been optimized, they were often not as ornamental as burnt gems. Moreover, depending on the weight of the gems, gems that were less than 1 carat on the market had no collection value.

If the weight exceeds 2 carats, 5 carats, or even 10 carats of gemstones, then they can be collected. The collection value is very large. Under the same weight, the price of unburned sapphires may be three times higher than that of burned sapphires.

If you tell if the gemstone is burned or not?

As a customer, they generally do not have the ability to identify burned and non-burned. The certificate issued by the gemstone appraisal agency shall prevail.

It is common to win the bidding in a certificate, such as a TGL certificate, which will be marked H in comments win the bidding.

No burn: "No indication of thermal treatment" or "No indication of heat present" indicates no burn/no signs of heat treatment.

Burning: "H" or "Indication of heat present" means burning/heat treatment.

For those in the gemstone industry, a multiplier is used to identify gemstones by observing their inclusions and color bands.

The following is the change of the inclusion and color ribbon in the gemstone after heating.