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What's the deal with sapphire treatments?

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shelovesinclusions

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I recently purchased a blue sapphire that Multicolour stated is heated. I don't mind heating, but I see other sellers list basic or high or low heat. I've tried to research, but cannot figure it out- does the presence of silk indicate heat to the point of silk development, high or low, or absence of heat?
 
A heated stone can still show silk. It’s not definitely proof of heat treatment. High magnification will show signs of heat/no heat. Other equipment might be needed to analyze whether it’s plain heat or other minerals were added to further improve colouration.
 
HI MissSarah,
yes there are different heating stages which are used. Normal (long time traditional) heating of corundum is around 1600 degrees if I remember correctly. But there are also developed some low heat processing which were developed in the past. E.G:
https://www.gia.edu/gia-news-research-low-temperature-heat-treatment-mozambique-ruby
The high heat is normally changing the color and clarity of a stone from milky white to probably blue. The low heat is often just to "adjust" a color by removing a blue hint. Also most of the inclusions dont dissolve here. Its detectable but far more complicated then high heat.
The problematic "heat" treatment is when diffusion (Be e.g.) or glassfilling is also involved. Sometimes the stones are stated as heated only (which is only partly correct) but are also glassfilled or be-diffused. So know your dealer or know a good lab for this ;)
Glasfilled is normally easier to detect, be-diffusion is far more difficult with easy instruments to see.
 
Many of us avoid heated sapphires for these reasons. I have never made a distinction between high- and low-heat when looking to buy, although I have seen it pointed out in various ads/listings.

There's no guarantee that an unheated stone is unadulterated; however, it takes a lot of the uncertainty out of the equation. It does constrain the size of what one can afford, though!
 
Thank you!
 
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