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THE IMPACT OF INTERNAL WHITISH AND REFLECTIVE GRAINING ON THE CLARITY GRADING OF D-TO-Z COLOR DIAMONDS AT THE GIA LABORATORY John M. King, Thomas M. Moses, and Wuyi Wang Unlike many other characteristics that affect the clarity grade of a diamond, determination of the impact of “whitish” graining and “reflective” graining requires analysis that goes beyond visibility at 10× magnification. The importance of this determination is further underscored by the fact that such graining often is the only characteristic present in large, high-clarity, high- color diamonds. This article reviews the history of reporting on such graining by the GIA Laboratory, considers the causes of the different types of graining most commonly encoun- tered, and examines the methodology and critical assessment GIA graders use to determine the impact of such graining on the clarity grade of a diamond. ne of the most misunderstood features in reflective graining typically consists of internal diamond clarity grading is the impact of reflective planes. O graining, especially internal “whitish” or Many of the forms graining takes (e.g., surface “reflective” graining (see, e.g., figure 1). R. E. Kane’s lines or colored bands) are readily observed, and 1980 Gems & Gemology article, “The Elusive their relationship to clarity can be understood with Nature of Graining in Gem Quality Diamonds,” standard diamond grading conditions and criteria gave the reader an overview of the causes of grain- (i.e., ease of visibility at 10× magnification and loca- ing, illustrated the range of appearances associated tion). But whitish graining and reflective graining with it, and generally outlined its relationship to are often more difficult to distinguish and relate to clarity grading at the GIA Laboratory (see also clarity, since their visibility is influenced more by Kane, 1982). The present article looks at this sub- optical factors such as the type of lighting and the ject 25 years—and literally millions of diamonds— angles of observation in relation to the lighting. later. For the purposes of diamond grading, graining refers to optical discontinuities that are observable Note: The photomicrographs provided in this article represent a static with a 10× loupe or a standard gemological micro- view of a graining feature, and are often taken from a viewing angle in which the feature is most obvious. It is important to remember that scope. The overall transparency of a diamond can one factor in determining graining’s impact on a clarity grade is the be affected by these discontinuities to varying effect of subtle movement of the diamond during observation. While extent. While fractures and cleavages are also dis- the feature illustrated in the image may appear obvious, the determi- nation mentioned in the caption reflects Laboratory awareness of all continuities, an important difference is that with the factors that influence the clarity grade. graining no open space (i.e., air/diamond interface) See end of article for About the Authors and Acknowledgments. is present. Whitish graining can be classified into GEMS & GEMOLOGY, Vol. 42, No. 4, pp. 206–220. banded, tatami, and overall haziness, whereas © 2006 Gemological Institute of America 206 IMPACT OF GRAINING ON CLARITY GRADING DIAMONDS GEMS & GEMOLOGY WINTER 2006 Figure 1. The 30+ ct pear shape and 18 ct oval shown here are representative of the large colorless to near- colorless diamonds in which whitish graining may affect the clarity. This effect is often mis- understood due to the elusive nature of such graining. The photomi- crograph illustrates a classic example of the cottony banding encountered in whitish graining that will have an impact on the clari- ty grade. Photo © Harold & Erica Van Pelt; photomicrograph by Vincent Cracco, magnified 21×. Also, because such graining is a natural part of the encountered in large (e.g., over 4 ct) diamonds. Most diamond structure, many trade members do not of these large diamonds are type II (a diamond type believe it should be a clarity characteristic. that is relatively free of nitrogen) and often absent of However, undeniably there are varying degrees of solid inclusions (see, e.g., Moses and Wang, 2006). visibility associated with whitish and reflective Another factor is that the complex interaction of graining, which has resulted in considerable debate light with a diamond’s cut when viewed in the face- over the impact it should have on the clarity grade up position may restrict the observation of this (Nir Livnat, pers. comm., 2006). often subtle, visually elusive feature to the pavilion, Other challenges to understanding the impact of where such graining can impact the most critical such graining on the clarity grade relate in part to clarity determination of Flawless/Internally the fact that a more complex decision-making pro- Flawless (FL/IF) versus VVS1 (figure 2). This rein- cess is required to assess whitish or reflective grain- forces the importance of consistent interpretation of ing than is usually required with most other internal this feature, given the potential impact on the value features. This process must take into account the of the diamond. ability not only to discern the feature at 10× magni- While reflective graining (figure 3) is observed fication, but also to determine its form (i.e., lines, more often in smaller, type I diamonds and fre- planes, broad areas), texture (i.e., cottony, sheen-like, quently in association with other inclusions, its hazy), and the angle(s) at which it is visible. assessment requires many of the considerations— In the early years of diamond grading at GIA, the and complex decision making—described above for complexity of assessing whitish graining was com- whitish graining. Therefore, this article will focus plicated by the fact that this characteristic was on assessing the appearances and grading of whitish encountered only infrequently at the laboratory. In graining in particular, with specific reference to recent years it has been further complicated (and its reflective graining where appropriate. importance enhanced) by other factors. For one, in Following an overview of GIA’s history of our experience whitish graining is most commonly reporting on graining (particularly whitish), we will IMPACT OF GRAINING ON CLARITY GRADING DIAMONDS GEMS & GEMOLOGY WINTER 2006 207 Figure 2. Illustrated here are two appearances associated with whitish graining that affects the clarity grade. These diamonds had no other internal features visi- ble at 10× and the graining was only seen through the pavilion, which resulted in a clarity grade of VVS1. Photomicrographs by Vincent Cracco; magnified 21× (left) and 15× (right). summarize the causes of whitish and reflective early 1970s indicates that it was not until this peri- graining and then describe the system GIA uses to od that diamonds with low diaphaneity were seen determine the effect of such graining on a dia- in the laboratory. The Spring 1970 issue of Gems & mond’s clarity grade. Gemology (p. 157) provides insight into the devel- oping awareness of this distinctive appearance when Crowningshield reported the following on HISTORY OF REPORTING AND CLARITY examining a “milky” diamond: GRADING WHITISH GRAINING AT GIA The evolution of grading whitish graining is an We were reminded of certain important dia- interesting case study of how diamond grading has monds we have graded recently that were just developed since its early days. As with many areas slightly misty but in which no zones nor paral- of study, in diamond grading the collection of data lel bands could be seen and no particles what- over time allows the observers to make refinements ever, even under highest magnification. Two and clarify the methods used to make assessments. such stones were top color and free of any imperfections otherwise. It was acknowledged This section presents an overview of the developing that the slightly lower transparency did affect awareness of this feature and changes in reporting the value, but we have been at a loss how to through the years. arrive at a meaningful grade. It is possible that While GIA has issued diamond grading reports these stones represent a new source of gem dia- since the mid-1950s, it was only in the late 1960s monds. If so, we must arrive at an acceptable and the 1970s that requests for its grading services grade for them so as to be fair to the diamonds began to grow. With the investment craze of the and to potential customers. late 1970s—when purchases of goods such as dia- monds, silver, and gold were promoted as a hedge The following year, Crowningshield (1971a) against inflation—demand for “certificate” goods speculated that these “grained stones” might be rose dramatically. This resulted in huge increases from Russia. However, diamantaire Louis Glick in report production and staffing at GIA. Even (pers. comm., 2006) recently confirmed that he and though the boom had become a bust by the end of others had purchased and manufactured similar dia- 1980, the trade was now using grading reports rou- monds in the late 1960s and early 1970s that origi- tinely in diamond transactions. In fact, laboratory nated from Sierra Leone. As more of these dia- records show that GIA graded more diamonds in monds were submitted to the laboratory, it became the decade of the 1980s than in the previous 25 clear that this feature often occurred in larger dia- years of diamond grading combined. monds high on the D-to-Z color grading scale. It Consequently, early reporting on diamonds also became apparent that this “misty” appearance with whitish graining was generalized, with broad was being seen in diamonds from many sources. categories for the appearances and descriptions Recognizing that the loss of transparency affected used. Several years elapsed before senior graders value, as mentioned above, the laboratory began to had examined enough diamonds with graining to systematically report on readily observed graining enable them to review and refine the grading crite- during the early 1970s.

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