METHOD FOR TREATING COLORED DIAMONDS AND BRILLIANTS FOR DECOLORIZING THEM AND RELEASING STRESSES Russian patent published in 2006 - IPC C30B33/02 C30B33/04 C30B29/04 B01J3/06 C01B31/06 

FIELD: decolorizing diamonds and brilliants.

SUBSTANCE: method is realized due to physically acting in closed reaction space upon samples of diamonds and brilliants by means of high pressure and temperature for time period sufficient for enhancing their quality. Pressure acting upon samples is in range 6 - 9 GPa in region of thermodynamic stability. Temperature during physical action upon samples is in range 1700 - 2300°C. Samples are subjected to physical action in medium of graphite powder filling reaction space. Heating till high temperature is realized due to applying AC to samples of diamond or brilliant through graphite powder at specific electric current power from 0.18 kWt/cm³ and more. Then electric power is gradually increased from zero till working value and further it is decreased and increased at least two times for some time interval at each change of electric power. Process of annealing samples is completed by smoothly lowering electric current power till zero. At physical action upon sample electric current intensity is lowered by 11 - 13 % and it is increased by 15 - 17 % for time interval from 8 min and more at each change of electric power. Sample is AC heated and it is cooled at rate no more than 0.05kWt/min per cubic centimeter of reaction volume of chamber.

EFFECT: shortened time period of treating for whole decolorizing, lowered voltage values, keeping of desired parameters existing before treatment in diamonds and brilliants.

3 cl, 3 ex