Heat treatment of a diamond

Diamonds have special optical properties such as high dispersion and lustre ( also known as adamantine ).  Heat treatment can enhance a diamond`s clarity and make it look spectacular. Clarity is one of the four Cs of diamond grading. Тhe others are carat, colour, and cut.

Unlike chemical treatment, heat treatment is safer, easier and the process already occurs in nature. Diamonds form in the Earth’s mantle where temperatures are at least 2000 degrees Fahrenheit (1050 degrees Celsius). They are delivered to the surface by deep-source volcanic eruptions which produce kimberlite and lamproite pipes. Mines are developed in these pipes when there is enough amount of diamonds.

Heat treatment was also a popular craft in the past. Artisans used to apply heat to gemstones in order to create new, more vibrant colours. Nowadays, induction heating can do the same for up to 10 -15 mins.

Equipment: EC-12


During the testing process in our laboratory, the diamond was heated up to 1840°С in an argon atmosphere. The heat treatment successfully improved the clarity and the colour density of the precious stone. The internal structure of the stone changed but was not apparent to the untrained eye. The smoky colour, which resulted from the heating process, was later removed with chemicals. As a result, the diamond now appears to be of a higher quality.


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