World Of Gems Conference 2017 Proceedings Book

WORLD OF GEMS CONFERENCE V - 13 - SEPTEMBER 2017 M yanmar produces the finest jadeite worldwide and the Chinese are the undisputable masters in carving it. Since the discovery of the rich jadeite deposits in Myanmar, nearly all the production has been marketed through mainland China and Hong Kong, in continuation of a jade (mainly nephrite) culture reaching back thousands of years. Today, the traditional way the Chinese appreciate “fei cui” (Cantonese) or “fei tsui” (Mandarin) jade clashes with the Western approach which is a purely scientific one: the mineral jadeite being an end-member of the isomorphous series of clinopyroxenes. The ability of jadeite to form solid solutions with other clinopyroxenes, com- bined with the chemical miscibility and retro- grade transformations occurring during the retrograde metamorphism add to the complex composition of jadeite and jadeite related gem materials. The Chinese have developed such a strong affin- ity towards jade that jadeite specialists distin- guish between several hundred varieties which are mainly characterized by their type of texture, degree of trans- parency, key color and color pattern; it is the combination of these features that define a jadeite variety. For example, the “moss-in-snow” variety holds some flecks of vibrant green on a white, near-opaque to opaque base. If this same color pattern is seen on a translucent piece of jadeite, it is a different variety. In the same way, jadeite experts distin- guish between 15 quality grades of so-called “imperial jade,” clarity grade not included. Thus, the author advises anyone who is not familiar with the Chinese terminologies and classification of jadeite varieties to avoid using them and applying solely descriptive visual features. Most Westerners in the gemstone and jewelry business struggle with jadeite because it does not fit into the “4C” concept used for quality grading of most gemstones, partic- ularly the transparent ones. Many gemologists attempt to in- tegrate jadeite into this popular concept; however, the author recommends avoiding it for several reasons. Jadeite varieties and sub-varieties are defined by a combina- tion of texture and diaphaneity of the base, color and color pattern. Further, other “fei tsui” varieties are additionally de- fined by their mineral composition. Jade experts distinguish a multitude of jadeite varieties. There are hundreds of green jadeite varieties alone. First, the base category must be identified regardless of its color; the base can be glassy, icy, oily, cooked lotus root-like, pea or porcelain. This step includes a range of grain size, a type of luster, and a range of diaphaneity. Secondly, the consistency of the texture must be as- sessed; it can range from uniform to very uneven. The quality of the base defines the degree of diaphaneity, which is also influenced by the color intensity, clarity and thickness of a jadeite item. Only once the quality of the fabric is assessed, one should go to the third step to de- scribe the color(s) and color pattern(s) (Figure 1). The finest quality of the base produces the highest quality and enable an even color spread. The fabric also influences sig- THE JADES OF MYANMAR/BURMA Roland Schluessel FGA, DGemG JADE ABSTRACT FIGURE 1.