Spectroscopic Characteristics And Coloring Mechanism Of Modified Pink-Red High Temperature And High Pressure Synthetic Diamond

In this paper,we studied the basic gemological characteristics,spectral characteristics and coloring mechanism of pink-red high temperature and high pressure(HPHT)synthetic diamonds produced by a company in China.It is expected that this study will not only provide a basis for the test of pink-red synthetic diamonds,but also provide theoretical basis for the research of synthetic diamond in the field of materialogy and physics.We used Gem microscope,Jewelry luminescence imaging analyzer,Diamond View^TM,Micro-infrared spectrometer,Ultraviolet visible spectrometer,Photoluminescence spectrometer,and X-ray fluorescence spectrometer to study 6 round bright cut pink-red HPHT synthetic diamonds.The results show that the opaque metal catalyst inclusions can be seen in this batch of diamonds are usually in the form of needle,(short)column,point and irregular shape,etc.Under the Gem microscope,obvious color partition can be seen,showing typical“hourglass”or irregular shape.Samples showing Luminous zoning under the Diamond View^TM,the Luminous partition of cube,rhombic dodecahedron and octahedron can be clearly seen from the table in some samples,showing a typical"dark cross"phenomenon;some samples only have obvious Luminous partition phenomenon through the table,but no"dark cross"phenomenon was observed,which indicates that the Luminous partition images observed with different diamond observation angles and cutting direction have obvious differences.All samples showed red to orange-red fluorescence,which was related to impurity or defects in the diamond lattice.The absorption band centered at 260nm can be seen in UV-Vis Spectrum,with the infrared spectrum of sample H-01?03 are 1131 and 1344 cm^-1 absorption peak and the sample H-04?06 only can be seen 260nm absorption band in UV-Vis Spectrum,indicate that the samples belong to type?b or type?b nearly type?a.The sample have(N-V)⁰defect at 575nm or(N-V)^—defect at 637nm,irradiation-related absorption at 741,595 and384nm,and absorption related to post-irradiation annealing at 1450cm^-1.In PL spectrum,there are also peaks at 575 and 637nm,which is the main reason for the appearance of pink-red color and red to orange-red fluorescence of diamonds.H3 center,GR1 center and588 nm absorption/luminescence peaks are the evidence of irradiation and annealing treatment.With the X-ray fluorescence spectrometer,it can be known that the fluorescence peaks of Cu,Fe,Ni,Zn and other elements were found in the X-ray fluorescence spectrum of the samples.Based on the analysis,the sample is type?b pink-red high temperature and high pressure synthetic diamond treated by irradiation and annealing.It is inferred that the color reaction mechanism is as follows:The diamond synthesized by high temperature and high pressure method,At first,an electrically neutral vacancy(V⁰)is produced by irradiation,and then after a medium-low temperature annealing treatment about 800?1000?produced(N-V)^0/-defect and other defects which makes the diamond appear pink-red.