Study Of Color Enhancement Experiment Processed On Synthetic Diamonds And Its Characteristics

In this paper,six CVD synthetic diamonds and two HPHT synthetic diamonds were treated for a better color,method of treatment includes HPHT annealing,irradiation and annealing.Every sample was treated by one or several of these processes.Measurement of Photoluminescence spectroscopy?FTIR absorbtion spectroscopy?DiamondView^TM were used before and after every treatment step.The result of this color enhancement experiment is:These type IIa CVD synthetic diamonds turned to purple-brown,pink,pink-purple and dark reddish-brown after the final treatment.After HPHT synthetic diamonds were treated,they became light yellow or reddish brown.The test result showed that some of the Ib nitrogen transformed to A defect after HPHT treatment,the yellow color became lighter and N3 center generated.In addition,after HPHT treatment,S3 center were formed,S2 center became stronger,and complex Ni-N defect was formed.GR1 center can be induced after irradiation and introduce blue tone,the final color can be green added by the original color.The GR1center produced by irradiation is easier to form in diamonds with A defect.In addition,interstitial defect can be formed accompanied by the formation of vacancy.After annealing at 800?,GR1 center disappeared and strong NV and H3 centers were formed,the sample became pale yellow.Strong NV center were formed after irradiation and annealing performed in as-grown HPHT synthetic diamond,the sample became dark reddish-brown for the original dark yellow color caused by Ib nitrogen.The sharp decrease of H3,N3 and NV centers after HPHT treatment in CVD synthetic diamonds indicates that nitrogen aggregation occurred.Strong H3 center can be produced in brown type IIa diamond after HPHT treatment at 1600?and the sample became light yellow.Some characteristic feature of CVD synthetic diamond at596⁵97nm and 3123cm^-1 disappeared after HPHT treatment.GR1 center induced by radiation introduced blue color,meanwhile interstitial defect were formed.Some of GR1 center were moved by annealing at 800?and captured to form NV,H3 center,which introduce pink and yellow hue.Most of the defects?ND1,647nm,722nm etc.?induced by irradiation disappeared after annealing,while GR1 center became weaker and 3H center became stronger.After irradiation,strong defect of 647nm and 722nm were induced in both HPHT synthetic and CVD synthetic diamond,these two centers disappeared after annealing at 800?,but the reason for these centers are still unclear.GR1 is the dominant form of vacancy caused by irradiation in both HPHT synthetic and CVD synthetic diamonds.After annealing,in CVD synthetic diamond with low nitrogen content,NV⁰ is the main form of NV center,while in HPHT synthetic diamond with high amount of Ib nitrogen,the main form is NV^-.