Can sapphires be heat-treated?

Over ninety per cent of the world’s natural sapphire supply gets heat-treated to intensify the colour and help the overall clarity. Yes, it’s fairly common. People consider it stable, permanent, and it is broadly accepted as a usual method in the global gem trade.

With heat treatment, pale, greyish, or even overly dark corundum can be changed into vibrant blues, pinks, or yellows. This happens because chemical impurities, like iron and titanium, are modified at a kind of molecular level. In addition, fine rutile inclusions can melt, so that what used to look cloudy becomes more transparent. Because of this, buyers should generally assume a sapphire has been heated unless it comes with a credible gemmological report stating it is unheated. Without that paperwork, the market value can drop hard, while a verified unheated stone typically commands a much higher price.