Kenji MIYAZAWA (1896-1933) grew up in a relatively wealthy family in the Meiji Era, and died young in the early Showa Era. He was very interested in gems, as described in his novel, “Bachelor Naranoki is an expert in gemmology.” Gem-quality diamonds and rubies do not occur in Japan, and in a letter to his father, he wrote that he was considering a career in gem synthesis. He may have intended to earn money to treat his sister’s illness with the profits from his job. His knowledge of such gems may have been obtained from Japanese publications as “Hoseki-shi（寶石誌）”. Miyazawa was one of those who studied minerals and gems at that time.

A diamond cutting factory which was the first and full scaled plant in Japan was established as a joint venture of a Japanese trading company and an American company, and started operation in April 1968. Experiments and experiences at the factory successfully achieved production of brilliant cut diamond preferred in Japanese market which was somewhat different from that of the Tolkowaky’s one. Also other matters such as the yield %, polishing efficiency, the characteristics for each cut stones and the profitability of the factory were examined.

About 20 years have passed since LA-ICP-MS came to be used in the gem identification field. At the same time, many researches using LA-ICP-MS have been published, but there is almost no explanation of LA-ICP-MS analysis in gemological articles. This paper focuses on the “principles” and “measurement methods” of LA-ICP-MS analysis, and describes problems and know-how related to analysis. In addition, I also describe the application examples that the author presented at The Gemmological Society of Japan in the past.