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Article type: Cover
1990 Volume 15 Issue 1-4 Pages
Cover1-
Published: November 30, 1990
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Article type: Index
1990 Volume 15 Issue 1-4 Pages
Toc1-
Published: November 30, 1990
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Article type: Index
1990 Volume 15 Issue 1-4 Pages
Toc2-
Published: November 30, 1990
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Iwao Umeda, Koichi Iida
Article type: Article
1990 Volume 15 Issue 1-4 Pages
3-11
Published: November 30, 1990
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Examinations of artificial coloration of jewelry diamonds are carried out by neutron irradiation using a research reactor or electron beam bombardment using a linear-accelerator, and subseqent annealing using an electric furnace. Most of examined diamonds are Ia type cut stones, and some samples ae rough stones and Ib type synthesized diamonds. The colored diamond hue depends on the treatment conditions and fancy hue can be produced under some suitable conditions. The aborption spectrum changes are introduced by the process of radiation treatment and subseqent annealing. The absorption spctra are obtained to observe the spectrum changes using double beam spectrophotometers at room temperature before-and-after radiation treatment and subseqent annealing for the same diamonds. Irradiated diamond colors are from blue to green and annealed diamond colors after irradiation are from lemon yellow to golden. However, low temperature spectroscopy has not been carried out in this examination to observe aborption bands for determinating whether the color of diamond is natural or man induced.
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Hiroshi Komatsu
Article type: Article
1990 Volume 15 Issue 1-4 Pages
12-21
Published: November 30, 1990
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Two samples supposed to be pearls which were excavated from archaeological shell mounds at Torihama, Fukui Prefecture (5500 years B.P.) and Chatsu, Hokkaido (4000 years B.P.) were investigated to clarify whether they are real pearls and what are the mother oysters. Based on the definition that pearls are the products of metabolism and have characteristic nacreous layer structure on their surfaces which are differenet from those of shells, the two samples were identified to be genuine natural pearls. Both exhibit characteristic nacreou layer to pearls. To identify the mother oyster, the results of chemical element analyses were used, which can indicate sea-water or fresh-water origin. Microscopic observations indicate whether the mother oyster is spirals or bibalves. Based on these results and spectrophotometric measurements, it was suggested that the mother oysters were fresh water bibalves for the sample from Torihama, and Modiolus difficilis (KURODA et HABE) for that from Chatsu.
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Junko Shida
Article type: Article
1990 Volume 15 Issue 1-4 Pages
22-27
Published: November 30, 1990
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Since distributions of micron size light scattering bodies (inclusions, precipitates, impurities, dislocations and other lattice defects) and the fluorescence emitted there from can be visualized by the laser tomographic technique and the electronic states associated with them may be modified by heat treatment, the laser tomography can be a future promissing powerful diagnostic technique in gemmology. This paper offers selected laser tomographic images which are characeristically seen in heat trated sapphire from Sri Lanka. Descriptions are given as to what sorts of images are characteristic to heat treated stones as compared to those obtained for untreated stones. Discussion is also given how the difference between treated and untreated stones arises.
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Yoshifumi Naito
Article type: Article
1990 Volume 15 Issue 1-4 Pages
28-36
Published: November 30, 1990
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Using green but opaque natural chromian diopside from Kamisano, Yamanashi Prefecture as nutrient and seed, transparent, emerald green single crystal boules of gem quality have been synthesized by the floating zone method. The syntheses were carried out by the travelling solvent floating zone method, using an IR convergent image furnace in nitrogen atmosphere. Nutrient rods of 1.5cm in length and 0.5cm φ were prepared by hydrostatically pressing the powders of natural samples. The conditions of growth and microscopic observations of the products are described.
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Ichiro Sunagawa
Article type: Article
1990 Volume 15 Issue 1-4 Pages
37-45
Published: November 30, 1990
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Geology and mineralogy of kimberlite pipes containing diamonds and observations of active diamond mining and dressing in Toudaogou area, Fuxian County, Liaoning Province, North East China are briefly described based on a recent visit to the area, as an excursion organized by the 15th General Meeting of the International Mineralogical Association. More than 100 kimberlite pipes have been found in the area, and a few pipes are economical and at least one pipe is being actively mined.
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[in Japanese]
Article type: Article
1990 Volume 15 Issue 1-4 Pages
46-48
Published: November 30, 1990
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[in Japanese]
Article type: Article
1990 Volume 15 Issue 1-4 Pages
49-50
Published: November 30, 1990
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[in Japanese], [in Japanese], [in Japanese]
Article type: Article
1990 Volume 15 Issue 1-4 Pages
50-52
Published: November 30, 1990
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[in Japanese]
Article type: Article
1990 Volume 15 Issue 1-4 Pages
53-54
Published: November 30, 1990
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[in Japanese]
Article type: Article
1990 Volume 15 Issue 1-4 Pages
54-55
Published: November 30, 1990
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[in Japanese]
Article type: Article
1990 Volume 15 Issue 1-4 Pages
56-57
Published: November 30, 1990
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[in Japanese]
Article type: Article
1990 Volume 15 Issue 1-4 Pages
57-58
Published: November 30, 1990
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Article type: Bibliography
1990 Volume 15 Issue 1-4 Pages
59-65
Published: November 30, 1990
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Article type: Appendix
1990 Volume 15 Issue 1-4 Pages
66-
Published: November 30, 1990
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[in Japanese], [in Japanese]
Article type: Article
1990 Volume 15 Issue 1-4 Pages
67-
Published: November 30, 1990
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[in Japanese]
Article type: Article
1990 Volume 15 Issue 1-4 Pages
67-
Published: November 30, 1990
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[in Japanese], [in Japanese]
Article type: Article
1990 Volume 15 Issue 1-4 Pages
67-68
Published: November 30, 1990
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[in Japanese], [in Japanese]
Article type: Article
1990 Volume 15 Issue 1-4 Pages
68-
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[in Japanese]
Article type: Article
1990 Volume 15 Issue 1-4 Pages
68-
Published: November 30, 1990
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[in Japanese]
Article type: Article
1990 Volume 15 Issue 1-4 Pages
68-69
Published: November 30, 1990
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[in Japanese]
Article type: Article
1990 Volume 15 Issue 1-4 Pages
69-
Published: November 30, 1990
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[in Japanese], [in Japanese]
Article type: Article
1990 Volume 15 Issue 1-4 Pages
69-70
Published: November 30, 1990
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[in Japanese]
Article type: Article
1990 Volume 15 Issue 1-4 Pages
70-71
Published: November 30, 1990
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[in Japanese]
Article type: Article
1990 Volume 15 Issue 1-4 Pages
71-
Published: November 30, 1990
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[in Japanese], [in Japanese]
Article type: Article
1990 Volume 15 Issue 1-4 Pages
71-
Published: November 30, 1990
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[in Japanese], [in Japanese], [in Japanese]
Article type: Article
1990 Volume 15 Issue 1-4 Pages
71-
Published: November 30, 1990
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[in Japanese], [in Japanese], [in Japanese]
Article type: Article
1990 Volume 15 Issue 1-4 Pages
72-
Published: November 30, 1990
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[in Japanese], [in Japanese]
Article type: Article
1990 Volume 15 Issue 1-4 Pages
72-
Published: November 30, 1990
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[in Japanese], [in Japanese], [in Japanese]
Article type: Article
1990 Volume 15 Issue 1-4 Pages
72-73
Published: November 30, 1990
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[in Japanese]
Article type: Article
1990 Volume 15 Issue 1-4 Pages
73-74
Published: November 30, 1990
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[in Japanese]
Article type: Article
1990 Volume 15 Issue 1-4 Pages
74-
Published: November 30, 1990
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Article type: Cover
1990 Volume 15 Issue 1-4 Pages
Cover2-
Published: November 30, 1990
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Article type: Cover
1990 Volume 15 Issue 1-4 Pages
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Published: November 30, 1990
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