Green to greenish blue to yellow green diamonds are a group of colored diamonds that generally owes its colors to natural irradiation - sometimes combined with natural annealing. The determination of the origin of color of such diamonds is the biggest challenge of the diamond market since such colors can be easily created by artificial irradiation - and laboratory annealing. The treatment-induced colors are caused by the same defects as the ones found in naturally colored diamonds and in consequence the distinction of natural color and treated color diamonds is difficult and sometimes even impossible. GGTL Laboratories Liechtenstein has worked on this problem since 2009 when an extensive and ambitious research project was launched that covers this topic; the project includes the analysis and characterization of naturally colored green to greenish blue to yellow green diamonds and the effects of artificial irradiation and annealing up to 2500°C on diamonds of all types and colors. The huge project that is still ongoing has enabled our laboratory to accurately identify the majority of these complex colored diamonds and to decrease the number of diamonds ending up with an undeterminable color origin.
This presentation by Dr. Thomas Hainschwang gives an overview of the many problems involved in the testing of these irradiation-related diamonds and will elaborate why it is so hard to give an accurate conclusion on their color origin. It will also cover the latest research results and why these represent a true breakthrough in the testing of such colored diamonds.