A diamond single crystal, which was synthesized at a high temperature of 1570 K and a high pressure of 5.5 GPa in a Fe-Ni-C system, was directly and systematically examined by transmission electron microscopy (TEM). I...A diamond single crystal, which was synthesized at a high temperature of 1570 K and a high pressure of 5.5 GPa in a Fe-Ni-C system, was directly and systematically examined by transmission electron microscopy (TEM). It is proposed that there exists a variety of imperfections such as dislocation loops, stacking faults, twins and stacking-fault tetrahedral in the diamond, which may be derived from the supersaturated vacancies generated during rapid cooling from high temperature. The formation process of the imperfections is discussed briefly.展开更多
This article provides an overview of the laboratory-grown diamonds seen at GIA over the last 15 years.During that time,the diamond industry has witnessed an exponential increase in the quantity and quality of laborato...This article provides an overview of the laboratory-grown diamonds seen at GIA over the last 15 years.During that time,the diamond industry has witnessed an exponential increase in the quantity and quality of laboratory-grown diamonds and,therefore,these products’ability to be commercialized on a large scale.It presents a brief summary of the HPHT and CVD growth processes and then explores some of the major trends observed since GIA began providing synthetic diamond grading reports in 2007.These trends include the shift towards larger and colorless stones.It also shows a shift towards CVD diamonds dominating the supply of laboratory-grown diamonds submitted for grading reports and that the majority of these have been subjected to post-growth HPHT treatment.In addition,we briefly discuss some methods and strategies used for identification such as the distinguishing gemological characteristics and some recent approaches in advanced testing.Finally,we present an array of laboratory-grown diamonds that are currently unusual,however,these may become more common in the future.展开更多
文摘A diamond single crystal, which was synthesized at a high temperature of 1570 K and a high pressure of 5.5 GPa in a Fe-Ni-C system, was directly and systematically examined by transmission electron microscopy (TEM). It is proposed that there exists a variety of imperfections such as dislocation loops, stacking faults, twins and stacking-fault tetrahedral in the diamond, which may be derived from the supersaturated vacancies generated during rapid cooling from high temperature. The formation process of the imperfections is discussed briefly.
文摘This article provides an overview of the laboratory-grown diamonds seen at GIA over the last 15 years.During that time,the diamond industry has witnessed an exponential increase in the quantity and quality of laboratory-grown diamonds and,therefore,these products’ability to be commercialized on a large scale.It presents a brief summary of the HPHT and CVD growth processes and then explores some of the major trends observed since GIA began providing synthetic diamond grading reports in 2007.These trends include the shift towards larger and colorless stones.It also shows a shift towards CVD diamonds dominating the supply of laboratory-grown diamonds submitted for grading reports and that the majority of these have been subjected to post-growth HPHT treatment.In addition,we briefly discuss some methods and strategies used for identification such as the distinguishing gemological characteristics and some recent approaches in advanced testing.Finally,we present an array of laboratory-grown diamonds that are currently unusual,however,these may become more common in the future.
