Among the treatments or enhancements done on gemstones, heat treatment is a process used to enhance the color, clarity, and overall appearance of certain gemstones. It involves subjecting a natural gemstone to controlled heating at high temperatures, often in the presence of certain gases or other substances. This process can improve or remove the gemstone’s color, remove or reduce visible inclusions, and create more attractive and marketable stones. The most common gemstones to which heat treatment is applied are blue sapphire, yellow sapphire, rubies, aquamarines, tanzanite, topaz, zircon, etc.
Temperatures used in this process can range from 500°C to 2000°C (900°F to 3600°F). The gemstone is heated slowly to avoid thermal shock, which could potentially lead to fractures or damage. Following are some of the main reasons why a gemstone is heat-treated:
This transformation can turn a lackluster gemstone into a vibrant and visually striking jewel. For instance, blue sapphires can be heated to intensify their blue color, resulting in a more vivid and desirable shade.
Inclusions, cracks, or other imperfections can be significantly reduced or even eliminated through heat treatment in gemstones. The process effectively enhances the gemstone’s transparency, making it more visually appealing. Gemstones that undergo this treatment often appear more brilliant and flawless.
Internal stresses within gemstones can be a concern, as they may lead to future cracks or fractures. Heat treatment in gemstones is instrumental in relieving these internal stresses, contributing to the long-term durability of the gemstone.
Some gemstones possess undesirable color tones or overtones that detract from their visual appeal. For instance, a gemstone may exhibit brownish or grayish hues that diminish its overall attractiveness. Heat treatment in gems can effectively remove or minimize these undesirable tones, resulting in a more pleasing gemstone.
The final objective of this treatment is to enhance a gemstone’s luster or brilliance. Heat-treated gemstones often exhibit a more captivating shine, making them more alluring to those seeking exquisite jewelry pieces. The improved luster adds to the overall desirability of the gemstone, elevating its market value.
Heated stone looks more beautiful and shines more than unheated stone. Although this type of treatment can indeed enhance the visual allure of gemstones, treated gemstones are generally less valuable than untreated ones. Untreated gemstones are often regarded as rarer and more authentic. Apart from this, according to astrology, unheated stones give you faster and more effect.
So if you want to wear any gemstone for astrological effect, then you should buy an unheated stone only. But it is also true that unheated stones are rare and difficult to obtain in the market.