World Of Gems Conference 2017 Proceedings Book

WORLD OF GEMS CONFERENCE V - 15 - SEPTEMBER 2017 JADES OF BURMA cracks they should not be misrepresented as fissures or cracks, or as healed fissures or healed cracks. Healing is not possible since the material has not been previously fissured or cracked. Figure 4. Jadeite occurs in a very wide range of colors, comprising pure colors, mixed colors, combinations of colors, multicol- ored and parti-colored with random or symmetrical color pat- terns. For Myanmar jadeite, these colors are generally classified into the following groups: green, purple, red to yel- low, white and black to gray, and multicolor (at least 2 addi- tional colors added to the color of the base). These color series not only reflect their visual appearance but to a certain degree, also their varying color origins. Blue, violet, lavender and pink Burmese jadeite belong to the purple group. Myan- mar blue jadeite shows a distinct color shift towards purple when moved from daylight to incandescent lighting condi- tions; this differs from Mesoamerican jadeite where blue jadeite is considered as a separate color. “Icy” jade is translu- cent to semi-transparent colorless jadeite which differs from white jadeite only by the texture/diaphaneity of its base. Gray to black jadeite owes its color to increasing contents of dark mineral inclusions. Most jade that appears black in normal lighting conditions but dark green in strong transmitted light, are kosmochlor jade. The appraiser faces multiple challenges to correctly value a jadeite item: • Correct mineralogical identification. • Treatment status. • Assessment of all quality criteria and their relative influence on the value. • Evaluation of premium factors such as historic aspects, artist and manufacturer, symbolism. • Access to reliable reference prices and/or similar comparison items. Due to the complexity of jadeite quality and value assessment, the author recommends a 5-step procedure for a reliable valuation of a jadeite item: • Identification: gemstone species & treatment status (texture inspection; Raman and/or FTIR; report from gemological laboratory). • First impression: Write down the value based on simple “guts impression.” • Quality grading: Carry out a systematic assessment of all quality elements, followed by a methodical valuation considering all value factors, including premium factors. • Compare: Check the item with a similar jadeite of known value. Trade show, manufacturers, wholesalers, retailers, auctions (do not rely on internet and strongly altered images). • Know your limits: Ask for a second opinion from a knowledgeable jadeite merchant. u REFERENCES George E. Harlow, Sorena S. Sorensen, Virginia B. Sisson and Guanghai Shi (2014). The Geology of Gem Deposits. Short Course Handbook Series Volume 37. Lee A. Groat, editor. Mineralogical association of Canada; Quebec, pp. 207-254. Cecilia Lam Shiu Ling (2001). Jade. Lead On Publishing Co; Hong Kong. Guanghai Shi, Xia Wang, Bingving Chu and Wenyuan Cui (2009b). Jadeite jade from Myanmar: Its Texture and Gemmological Implications. Journal of Gemmology, 31, pp. 185-195; Gemmological Association of Great Britain; London, GB. Ou Yang, Chiu Mei and Humphrey Yen (2015). Fei Cui – Jade: A Stone and a Culture. Shanghai Translation Publishing House; Shanghai, China. FIGuRE 4. A micro-shear zone reaching the surface of a green jadeite cabochon. Magnification: 36X. Photo by Roland Schluessel.