Gemstone Review – Heat Treatment of Sapphires – All About – sapphire gemstone
sapphire gemstone –
Historically speaking: Heating of gemstones to enhance their color goes back centuries. It is considered a natural type of treatment since the process is basically a continuation of the processes that occur in the ground. The stone is heated to a very high temperature, which causes the inclusions to minimize and improve color quality. Without heat treatment the world would be without many colored gemstones. Because colored gemstones occur in the colors that we see, are very rare. So, it’s nothing new, only highly refined process, simulating natural earth processes.
Permanence: By and large, heat treatment is permanent in nature. There are a few rare exceptions of heat treated gems losing color, but those are lesser known gems like kunzite. So, heat treated gems can be worn on a daily basis.
How does heat treatment affect a sapphire? A rearrangement of atoms takes place due to exposure to high heat. This happens in case of gouda sapphires, which are milky white and turn blue. Otherwise, the inclusions, so common in sapphires in their unheated state are significantly cleared.
How does it affect the cost? A 3 carat natural blue sapphire can cost about $ 20,000; and the price will go up significantly with the size of the stone. But if the sapphire has been heat treated, the same size could be available as low as $ 1500! Other factors, of course, will play their roles in the cost. What this means is, that if the jeweler is revealing heat treatment to you, it’s better.
Identification. There are a number of ways to identify heat treatment in sapphires. The first is to find the halo effect around included crystals. This is where the inclusions caused fracturing of the stone when the heat was applied. However, be sure to go to a trained gemologist for this kind of an identification.
So, why are treatments given? As stated earlier, clarity and color characteristics of a gemstone improve dramatically with heat treatment. This is done in proper and controlled conditions. We would not be able to recognize so many gems as we know them to be, were it not for heat treatments.
What are other treatments that sapphires are given? Diffusion:
Diffusion is an enhancement method, commonly used with corundums.( Sapphires and rubies are both corundums). The process lies in adding iron and titanium during the heating process of a gemstone. Sometimes it is called surface diffusion. In this, a layer is created on the surface. This layer is described as colored coating. By re-cutting, polishing or scratching diffused gems may alter in appearance.
Irradiation means pounding a material with subatomic particles. In some cases, irradiation is followed by heating to produce a better color of the gem.Today, many irradiation techniques are applied. Through this method, dark pink tourmaline can change into red. Irradiation treatment is believed to be permanent.
– Heat Treatment of Sapphires – All About
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