April 2021 | Lab Grown Magazine

To advertise call (888) 832-1109 | April 2021 31 A Diamond Services tech uses spectroscopic analyses in determining a diamond's origin. At right is a mounted stone in jewelry being tested at -170 o C. The spectroscopic measurement of the diamond suffers from a major obstacle due to the small concentration of the color centers to be detected. Thus, like in many other similar configurations, it is difficult to separate the contribution from the specific transition one is interested in from the background signal. For efficient measurement, the background signal has to be reduced, and this is best done by performing the measurement at low temperature, normally, liquid nitrogen. A typical telltale signature of lab-grown diamonds includes, for example, the silicon-vacancy (SiV) Photoluminescence peaks at 736.6 and 736.9 nm, which originated from silicon impurities hardly ever found in natural diamonds. However, in any measurement there is a strong background PL signal at these frequencies coming from the main diamond crystal, and it is this background that should be controlled. This situation is known and is common to many other spectroscopic measurements such as Raman. after manufacture, had been subject to HPHT heat treatment or other annealing processes. As Diamond Services believes that a treatment is a treatment regardless if it is done on a natural or grown stone, it started indicating treatment on grown stones some two years ago. At this stage, to the best of my knowledge, DS is the only company to offer this service in diamond-set jewelry. There is a built-in challenge when it comes to spectroscopically measuring diamonds, and it comes as the resultof thevery tight concentrationof thecolor centers thatneed tobedetected.For example,a telltale signature of LGDs involves silicon-vacancy photo- luminescence, which peaks at 736.6 and 736.9 nanometers. It originates from silicon impurities that are not present in natural diamonds, but, almost invariably, there is a strong background photoluminescence signal at those frequencies coming from the main diamond crystal, making it difficult to distinguish one from the other. For efficient measurements to be made, the background signal has to be reduced. This is best done by conducting the measurement at extremely low temperatures, which can be achieved by cooling the stone to about -170°C with liquid nitrogen. This is a procedure that, at present, can only be reliably performed in a properly equipped laboratory. In 2016,we made the strategic decision to suspend our strategy of delivering stand-alone detection sys-