Figures of the Article

• (a) On the left, some photomicrographs of the more common inclusions seen in HPHT-grown diamonds are pictured. These often include thin metallic rods. Also shown are some common observations of deep UV fluorescence imaging. In fancy-color diamonds, a variety of colors may be seen. However, in colorless to near-colorless HPHT diamonds, the deep UV fluorescence images are consistently a greenish blue color. (b) On the left, some photomicrographs of the more common inclusions seen in CVD-grown diamonds are pictured, which often include pinpoints or clouds of non-diamond carbon. Also shown are some common observations of deep UV fluorescence imaging. In CVD diamonds, even for those are colorless to near-colorless, there is a wide variety of possible fluorescence colors due to the growth conditions and possible post-growth treatments. Often the patterns seen in CVD diamonds will consist of obvious growth layers (center images) or striations (far right).
• Laboratory-grown diamonds have become an important sector of the gem diamond trade. The background image illustrates that many CVD-grown diamonds may be manufactured simultaneously by using multiple seed plates within the reactor. © Fraunhofer IAF.
• This photo sequence of a growing CVD sample within the CVD reactor shows the progression in thickness over time. The edges become significantly rougher as non-diamond carbon forms on those surfaces. The red color for the CVD diamond is because the sample is photographed within its growth environment and while at the growth temperature of ~1 000 ℃. The initial dimensions of the plate are 7×7 mm.
• The percentage of HPHT-grown diamonds submitted to GIA in each calendar year beginning with 2007 when synthetic diamond reports were first issued and extending through 2021 (year-to-date: January-September) and the color distribution.
• The percentage of CVD-grown diamonds submitted to GIA in each calendar year from 2007-2021 (year-to-date: January-September) and the color distinbution.
• The percentage of HPHT-grown diamonds submitted to GIA in each calendar year from 2007-2021 (year-to-date: January-September) and the weight distribution.
• The percentage of CVD-grown diamonds submitted to GIA in each calendar year from 2007-2021 (year-to-date: January-September) and the weight distribution. Due to very low submissions during some calendar years, those years have been combined.
• (a) The percentage of CVD-grown and HPHT-grown diamonds submitted to GIA in each calendar year from 2007-2021 (year-to-date: January-September); (b) The percentage of CVD-grown diamonds submitted to GIA in each calendar year from 2007-2021 (early years combined). A tiny percentage of CVD-grown diamonds have gemological and spectroscopic features that do not currently permit a treatment designation and receive an undetermined result regarding post-growth treatment, these are not included within the figure.
• Distribution of diamond types among colorless to near-colorless diamonds based on origin and treatment history (Eaton-Magana et al., 2020).
• (top) This 3.23 ct, I-color, as-grown CVD diamond is presented with the results for the deep UV fluorescence imaging and the results for PL mapping of the table facet using 532 nm excitation and with the diamond submerged in liquid nitrogen. This sample shows multiple grown layers with SiV^- showing the highest concentrations near the growth interfaces (Dieck et al., 2015). (bottom). This 0.42 ct Fancy Deep green, treated HPHT diamond shows the different growth sectors by deep UV fluorescence imaging and PL mapping using 633 nm excitation and liquid nitrogen. The SiV^- concentration is confined to the {111} growth sectors (Johnson and Myagkaya, 2017).
• (a) This 0.33 ct Fancy blue diamond has a CVD-grown layer which is 0.08 mm thick and adds approximately 0.01 ct of weight (Moe et al., 2017). The interface between the natural and CVD layers is obvious when observed by deep UV fluorescence imaging. (b) This 0.65 ct CVD-grown diamond has Fancy brown-pink as its stable color, but converts to a Fancy Intense blue with deep UV excitation. (c) A 0.42 ct Fancy Deep green, 0.47 Faint yellow-green, and a 0.51 ct very Light green HPHT-grown diamonds (clockwise from left) received their color from high amounts of nickel doping. At right is the visible-NIR absorption spectrum for the 0.51 ct very light green HPHT-grown diamond (Johnson and Myagkaya, 2017; Eaton-Magaña, 2019).