Analysis Of Gem-Quality And Experimental Estimation Of Toleration Ranges In Geometrical Features Of Brilliant Type Cut Diamonds

Abstract

The measures that influence the quality of diamonds are cut, shape, colour, clarity and weight. These features are therefore of some economic significance. It has long been recognized that similar type diamonds with identical cuts are subject to some variability in geometrical features that can give rise to differences in their quality. In the present study a brief review is presented of previous investigations that looked at properties of diamonds. This is followed by an overview of current practices in estimating the quality of diamonds with particular focus on brilliant type cut diamonds. The results are presented with prominent dimensional features, namely, girdle diameter, table, crown, girdle width, pavilion and their corresponding angles that were measured on 12 stones, six in each of 2 sets, ‘as bought’ brilliant type cut diamonds from one supplier. Variations in scatter and the mean value of each dimensional feature between the two sets of diamonds were estimated using relevant statistical methods. The results are discussed in the paper from both a qualitative and a quantitative point of view. It is suggested that this sort of information may be used to assist in assessing the quality of brilliants and selecting geometrically similar stones for jewels, when needed.