Research on the quality of large cubic gem diamond crystal

In this paper, high quality hexahedron diamond crystals were grown via the temperature gradient under high pressure and high temperature (HPHT), which is between 1300°C and 1350°C. The crystals were grown based on the steady growth of the high quality big single crystal through rational adjusting the crystal bed high to 5 mm. The results show that the weight of the crystal is 2.04 carat in 30 h, and the growth rate by weight was achieved to 13.6 mg/h, which was far much higher than samples from Sumitomo Corporation of Japan and Element Six Corporation. The lattice crystallization degree was lower than the Sumitomo Corp. sample, but higher than that of the Element Six Corp. sample. The strong diamond Raman standard peak was appeared in the 1332 cm-1 place of our diamond samples by the Laser-Raman test, and the half tall wide value of the Raman peak is 5.570 cm-1 by the Gaussian simulation. The average nitrogen content of our diamond samples was 240 ppm of the {100} faces, which was much higher than the Sumitomo and Element Six samples, because of the existence of impurity in the test conditions.