Lab-Grown Colored Diamonds From Chatham Created Gems

Abstract

ne of the most important gemological developments in recent years has been the commercial availability of jewelry-quality synthetic diamonds. What for almost three decades was primarily an industrial or research product is now becoming a commodity in the gem and jewelry marketplace. In addition to the products being offered by such companies as the Gemesis Corp. and Lucent Diamonds, Chatham Created Gems of San Francisco, California, has introduced a line of synthetic diamonds from a new source (figure 1). This article presents results of our examination of a large group of these high pressure/high temperature (HPHT) laboratory-grown diamonds in yellow, blue, green, and pink colors showing a full range of saturation, from weak to strong. Our examination indicates that most of the yellows and blues represent "as-grown" colors (i.e., those produced by nitrogen and boron impurities during diamond crystallization), while the greens and pinks are the result of either growth or growth plus post-growth treatment processes (i.e., irradiation, with or without subsequent heating). A single manufacturer is supplying Chatham Created Gems with approximately 500 carats of synthetic diamond crystals per month, with future increases in production planned (T. Chatham, pers. comm., 2004). The material is faceted in China into cut goods that range from a few points (melee) to as large as 2 ct. Chatham Created Gems is the sole distributor of this material for jewelry purposes. Previous gemological reports on synthetic diamonds produced in Russia and sold by Mr. Chatham (see, e.g., Scarratt et al., 1996) may not be applicable to the new HPHT-grown material described here, which is grown in Asia with a non-BARS press. This article provides information on material from all four color categories of this new product, including descriptions of green and pink synthetic diamonds, which have not been reported on extensively in the gemological literature. Most of the green samples display this color because they contain both blue and yellow growth sectors. Some of this new material displays hues and weaker saturations that more closely resemble natural diamonds 128

Spectroscopic analysis of microdiamonds in ophiolitic chromitite and peridotite

“…However, we did not observe Raman-active water and CO 2 -rich microinclusions in both microdiamonds and HPHT synthetic diamonds. Instead, we found metallic flux inclusions in the HPHT synthetic grits, as reported in previous studies (Shigley et al, 2004).…”

“…6). This peak was reported in Chatham synthetic diamonds, and attributed to nickel defects (Shigley et al, 2004). It can also be observed in natural diamonds (Adams and Payne, 1974;Hainschwang and Notari, 2004).…”

Strongly Colored Pink CVD Lab-Grown Diamonds

“…The trace amounts of isolated nitrogen needed for such a treatment (1) can occur naturally in the starting materials (i.e., as in type Ib diamonds), (2) can be generated at high temperatures by disaggregation of other nitrogen-bearing defects in natural diamonds through HPHT treatment, or (3) can be incorporated during synthetic growth. Treated orange, pink, or red diamonds from natural starting materials (Wang et al, 2005c;Wang, 2009) and from HPHT-grown synthetic starting materials (Shigley et al, 2004) have been well documented. The samples described in this study, however, are the first group of CVD synthetic diamonds GIA has examined with pink color caused by NV centers, and this also was documented in treated-color red natural diamonds in which the NV centers were produced by HPHT annealing and subsequent irradiation and annealing at relatively low temperatures (Wang et al, 2005a).…”

A History of Diamond Treatments

“…Though not directly addressed in this article, which focuses on natural diamonds, it is important to note that gem-quality synthetic diamonds are potential candidates for all of these color and clarity enhancement processes. Irradiation and heating treatments have already been used to produce red, pink, and green colors in synthetic diamonds (Moses et al, 1993;Shigley et al, 2004;Schmetzer, 2004), just as they are used with their natural counterparts. Shigley et al (1993) described several synthetic diamonds whose colors had been modified by HPHT annealing.…”