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We offer treatment solutions and consultations on treatment and processing of carbon materials and structures.

We also provide consultations in many fields of research and technology of diamond and other carbon materials.

A common commercial application of LPHT Treatment is the removal of brown color of CVD diamonds. Brown color of CVD diamonds is less stable than the brown color of natural diamonds. It can be substantially reduced and eventually eliminated by LPHT treatment at temperatures from 1800°C to 2000°C. LPHT annealing in combination with electron/gamma irradiation is an effective method of production of colored diamonds.

CVD diamonds of green, yellow, pink, orange, orange-red and blue colors can be produced using LPHT/irradiation treatment. Some unusual colors like “floating blue” and “cloudy black” are possible too. The picture below shows blocks of magenta color and two cut stones of yellow, orange-pink and blue color produced from originally brown CVD diamonds using multistep LPHT/irradiation treatment.

Annealing of diamonds at high temperature (HT) is a common method of their color treatment. The heating can be performed at high pressure (so called HPHT treatment) and low pressure, e.g. in vacuum (so called LPHT treatment). The transformations of optically active defects responsible for diamond color occurring at high temperatures are the reason of color changes.

The most common example of the high temperature color treatment of diamond is the discoloration of brown natural and CVD diamonds. Since LPHT treatment is simpler and more cost effective as compared with HPHT treatment, it is becoming the method of choice for commercial production of colorless and near colorless diamonds.