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JADE — Dyed jadeite: A report with an unusual twist comes from Yoshiko Doi of the Association of Japan Gem Trust in Tokyo. It seems that a quantity of small green jadeite cabochons that recently reached the Japanese market have been represented as being dyed. However, testing by Japanese gemologists revealed no evidence of dyeing. Believing that a new treatment method might have been developed, Ms. Doi sent some of the stones to the Santa Monica Gem Trade Laboratory for further testing. A refractive index of 1.66 and specific gravity of 3.33 confirmed that the material was jadeite. As expected, the stones were inert to ultraviolet radiation. Absorption lines in the red were consistent with the spectrum of a natural-color green jadeite. There was no evidence of any dye in the cracks when viewed with a microscope (see figure 11). All tests indicated natural-color green jadeite. As further confirmation, a piece of the jadeite was sent to Dr. George Rossman at the California Institute of Technology. A thin section of the stone was prepared and run on their Cary spectrophotometer. An absorption spectrum run from 350 nm to 1500 nm revealed a slight trace of Cr³⁺, with minor peaks at 434 and 439 nm and predominant peaks at approximately 638, 656, and 688 nm that were attributed to Cr³⁺. No extraneous features were present. This analysis is entirely consistent with natural-color green jadeite. It is still a mystery why anyone would want to represent natural-color jadeite as being dyed, but there is no doubt that the material tested was indeed natural color. Our thanks to Dr. Rossman for the detailed absorption spectrum. Dyed nephrite: Both the Los Angeles and the New York labs recently had the opportunity to study a flat, green 1.06-ct cabochon (figure 12) that had been presented as dyed nephrite jade. The client claimed that this material had retained its color better than the dyed jadeite he had. The cabochon was fairly translucent and, although slightly mottled, resembled fine green jadeite in color. However, the refractive index and specific gravity proved that the material was nephrite jade. The translucent crystalline aggregate structure was visible under magnification, with the green color concentrated within and around the fine cracks (see figure 13). Spectroscopic examination showed a broad absorption band (figure 14) in the red portion of the visible spectrum from 6600 to 7000 Å, which undoubtedly can be attributed to the green dye. However, only the faintest brownish color was seen under the color filter. This contrasts with the red color usually associated with dyed jadeite or serpentine. We have observed dyed nephrite only once or twice in the past (see, for example, the mottled carving pictured in the Winter 1965–1966 issue of Gems & Gemology). One theory about why there is not more dyed nephrite is that possibly the structure of nephrite resists the crackling necessary to take dye.