Emerald is a member of the beryl family; it is composed primarily of the abundant elements silicon (Si), aluminium (Al), and oxygen (O). The fourth main component, beryllium (Be) is rare in Earth’s upper crust. Thus, beryl is not a common mineral.
For emerald, the most appreciated member of the beryl group, the conditions of formation are quite peculiar. The elements that give emerald its bright green colour (chromium, Cr and vanadium, V) are concentrated in rocks of the upper mantle, not in the Earth’s upper crust. Therefore it needs unusual geologic and geo-chemical conditions to bring all these elements together. Normally, this happens through the actions of plate tectonics.
Once the necessary elements have been brought together, emeralds can crystallize in diverse geologic environments that, in general, are quite perturbed. While other beryls (like aquamarine) develop in relatively calm environments which allow for continuous crystal growth without strong perturbations, emeralds are formed in geologic environments characterized by abrupt changes and mechanical stress. This is the reason why emerald crystals are generally small (compared to the other members of the beryl family) and contain considerable internal defects such as fissures or foreign solid inclusions. Emerald crystals have a low mechanical resistance and do not withstand the stress of river transport. Therefore, emerald is rarely found in secondary deposits, all emerald deposits of economic interest are restricted to primary rocks.
The emerald deposits belong to different genetic types. They can be classified into two main groups: (1) Emerald crystallization associated with pegmatite and (2) Emerald crystallization not associated with pegmatites. Pegmatites are involved in the formation of the emeralds/beryls of Central Nigeria. These pegmatites have no schist seams; the emeralds are found in granite- and pegmatite vugs. In the Ural Mountains (as well as in some African and Brazilian deposits), pegmatites (and Greisens) with schist seams are present; emeralds are found in pegmatites and phlogopite schists (especially in contact zones).
The second genetic group of emerald deposits is related to metamorphic schists (e.g. Habachtal, Austria; Swat Valley, Pakistan; Santa Terezinha de Goias, Brazil; Panjshir Valley, Afghanistan) or black shales with veins and breccias (Colombia).
Emerald deposits are known from five continents, with South America having been by far the most important emerald producer for many years. Emeralds formed during almost every geologic epoch. The most intense emerald formation occurred during continental collisions, which gave rise to large mountain complexes, extended fault zones, regional metamorphic overprints and eventually to further uplift and erosion. All of these events favour the formation of emerald deposits. Emerald can, therefore, take its place among the oldest gemstones in the Earth»s crust: the oldest emerald deposits are those of Transvaal in the Archean of South Africa (almost 3 billion years); the youngest of the Earth’s emerald deposits are found in Pakistan: Swat Valley (23 million years) and Khaltaro (9 million years).
In our lecture, the situation (infrastructure, mining aspects; production, etc.) in the most important emerald deposits all over the world will be shown in detail (e.g.): South America (Colombia, Brazil), Asia (Ural Mountains, Pakistan, Afghanistan), Africa (Egypt, Zambia, Zimbabwe, Madagascar).
The specific mineralogical-gemmological properties of emeralds will be discussed: (1) Inclusion features; (2) Chemical fingerprinting; (3) Absorption spectra; and (4) Optical data. Objectives, criteria and limitations of the origin determination of emeralds, which are based on these properties, are addressed.

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Recently, we had a chance to test about artificially the irradiated diamond, so called the ice-blue diamond popular among a consumer. It presents the colour that is lighter than usual artificially irradiated diamond. We got the opportunity to examine diamond before changing a colour by the irradiation. We investigated the difference between the ice-blue diamond and natural blue diamond by using photoluminescence.

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The near-colourless single crystal of CVD diamonds were observed by using the optical microscope, an instrument of cathodoluminescence, and the Diamond View. CVD diamonds included the growth lines parallel to {100} and showed the characteristic that were different from natural diamonds. We observed an anomalous birefringence pattern, distinctive spectra of the infrared absorption and photoluminescence. CVD diamonds showed the spectra of infrared at 6855cm-1 and the spectra of photoluminescence at 737nm, 533nm and N-V center.

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Epitaxial diamond was grown on the type-Ib diamond (100) substrates using a microwave plasma CVD system with nitrogen addition in the methane and hydrogen source gases. In order to obtain high growth rates, we designed the substrate holders to generate high-density plasma. The growth rates were ranged from 30 to 120 m/h. The nitrogen addition enhanced the growth rate by a factor of 2, and was beneficial to create the macroscopic smooth (100) face avoiding growth of hillocks. However, the (100) surfaces looked microscopically rough by bunched steps as the effect of nitrogen addition. The macroscopic smoothing during the growth enabled the long-term stable deposition required to obtain large crystal.

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[in Japanese]

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High pressure synthetic diamond has been heat treated in graphite powder under a high pressure condition of 6 GPa and 1800 C. The heat treatment produces plastic deformation at edge of the diamond. According to cathodoluminescence measurements of the diamond, it was found that the 2BD luminescence bands, which are observed in brown type II natural diamond, are produced with the heat treatment, indicating that the luminescence bands are related to plastic deformation. Another type II diamond subjected to the heat treatment was found to exhibit a sharp line at 260 nm, which is also observed in type II natural diamond after heat treatment, indicating that this line is also related to plastic deformation.

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[in Japanese]

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[in Japanese]

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The cause of the colouring of emerald did to be Cr³⁺ and Nassau did an explanation by the crystal field theory. As for the green jadeite, the performer showed that Cr³⁺ caused the colouring as emerald year before last. This time, it reports the example which becomes a green gemstone with Fe³⁺. As for being coloured by the V ion and the Ni ion of the transition metal, too, using the crystal field theory, it examined the cause of the colouring. As a result, the difference of the absorption spectrum was proved. The absorption spectrum around 450 nm shifts the following in turn to the side of the shortwave length.
Cr³⁺-Fe³⁺-V³⁺ -Ni²⁺
In the theoretical explanation of the absorption spectrum of the gemstone, the crystal field theory is one of the valid techniques.

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[in Japanese]

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Unusual appearance of rough basal face on natural quartz crystals is analyzed to represent the form of transitional stage during overgrowth on fractured and partially dissolved rounded surface of earlier formed quartz crystals. The conclusion was obtained through the observations of heterogeneity revealed by cathodoluminescence in amethyst from Four Peaks(Arizona) and bipyramidal quartz from China.

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Introduction: Labradorite feldspar minerals becomes gem with iridescence as labradorescence (Miura et al.,1975). This gem mineral has problem of formation as initial state. a) The gem plagioclase can find limited regions with irregular texture of dark rocks with Fe grains. b)This type of gem minerals cannot be found in lunar and Martian rocks, except glassy plagioclases of maskelynite. The main purpose is to elucidate of these unsolved question by new consideration.
New Interpretation and summary: Iridescent labradorites with lamellar texture can be formed from impact glassy feldspar with heterogeneous brecciate texture to solid reaction under magmatic heating, which locations are satisfied for Canadian and Madagascar gems on the Earth. It is possible to find in Martian surface if condition is satisfied.
Authors are appreciate for discussion on lunar and Matrian rocks for Dr.G. Nord.

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I discuss about the difference of the nacre structure and intersection board structure that are the main structure of each shell.
I test the physical properties such as specific gravity, hardness, fluorescence, and magnetism rate.
With the identification method that depends on these differences, I mention each method on the nucleus and the pearl, furthermore I discuss the accuracy based on a destruction test.
I discuss about the issue of the nucleus made of Giant Clam from the influence of Washington Convention, passing year change, and brilliance.

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I chose three of the thin layer, the processing damage, and the crack of layer as the typical defect.
1. About the thin layer, I discussed the correlation of thickness of the nacre and passing year change by using the acceleration test mainly by the cycle of the high temperature/low temperature.
2. About the processing damage, I searched the actual condition of the nacre destruction mainly from interior structure.
3. About the crack of layer, I discussed about the progress of the crack by the observation method, occurrence mechanism, and disintegrate by aging.

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I discuss those spectra patterns about the representative "colour and tone" sample of the goldish pearl of an Akoya pearl.
I indicate those spectrum patterns by choosing the several kinds of orangish and yellowish dispersion-dye.
Then I discuss what kind of influence to each "spectrum-patterns" is exerted mutually about these samples goldish pearls coloured with those dispersion dyes.
Furthermore I discuss even the result of the wilt test of the sample coloured pearl.

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