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Diamond is a mineral grown in the earth's interior. Growth environments of natural diamonds are deeper than 150 km from the surface of the earth based on the thermo-dynamical stability of diamond. Natural diamonds often contain inclusions which were fragments of inside of the earth. The presence of inclusions debases the value of diamonds, but inclusions provide valuable information for earth science. Diamond is a physically and chemically stable material, inclusions in diamonds can retain information of the deep earth. By studying inclusions in diamonds, we can investigate chemical composition, isotopic composition, redox state, etc. of the deep earth where diamonds formed.
How can we investigate the depth origin of diamonds? It is possible to estimate the depth origin by observing inclusions in diamonds. Most of inclusions contained in natural diamonds are silicate minerals. These mineral inclusions were trapped in diamonds in the deep mantle and entrained to the surface of the earth. Difference in thermal expansivities and compressibilities between a host diamond and an inclusion induces differential stress between the diamond and inclusion. The differential stress can be observed as residual pressure in inclusions of diamonds (Navon, 1991; Schrauder M. and Navon O., 1993). The residual pressure can be measured from subtle frequency change in Raman spectra of diamond around an inclusion. By measuring the residual pressure, we can estimate the depth origin where a diamond trapped the inclusion.
I will introduce the spectroscopic properties of diamonds and the application to the investigations of the diamond origin including our research activities in my talk.
References
1) Navon O. (1991) Nature 353, 746-748.
2) Schrauder M. and Navon O. (1993) Nature 365, 42-44.

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We had discussed from various angles the correlation between the optical interference in the outer layers of pearls that generate Teri, and the crystal layers of pearls. Those discussions had been reported previously to The Gemological Society.
This last time, we did the following studies:
1) We roughly classified the colors and designs created by this phenomenon of interference into three patterns, and tried to get their precise photo images. Then, we measured the crystal layers of those pearls, depicted the colors and designs from the thickness of a single layer, and compared those colors and designs with actual photo images. The result showed that they approximately matched each other.
2) In order to study the main factor - irregularities in the crystal layers - that influences the degree of interference, we analyzed images from the scanning electron microscope (SEM). The result showed a consistency in thickness.

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We conducted the following on the processing flaws (such as cracks or spots) that presumably had occurred because of inadequacies during the preliminary process.
1) We observed forms and structures of flaws under an optical microscope. We inferred that the flaws had been caused by stress due to the expanding and contracting of the nacreous layers.
2) Next, we did acceleration tests to determine how those processing flaws would develop and become more obvious with the passage of time.
3) We went on to apply expanding and contracting stress to flawless pearls, and tried to replicate the same sort of processing flaws.

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At present, the light transmission method is the only way to distinguish natural blue pearls from blue pearls treated with radiation that browns their nuclei. However, even with this method, it is often very difficult to differentiate the two sorts of pearls, depending on the development or distribution of heterogeneous layers inside the pearls.
If we look only at the nucleus, we see that the one that was treated with radiation (a) has turned brown, and (b) has lost its fluorescence under exposure to ultraviolet rays. The light transmission method is a method of distinguishing based on the former effect (a); this time, we created a way to differentiate that depends on the latter effect (b).
The nucleus is made by shaping the nacreous layer of the shell of Anodonta woodiana (a fresh-water shellfish). We inferred that the disappearance of fluorescence in the nucleus might be related not to the aragonite that is a component of the nacreous layer, but to a protein that is another component. We did some experiments to verify this.
Next, we inserted a scraper into a hole in a pearl, and collected a modicum of powder from the sides of the hole. We observed the powder under a fluorescence microscope and were clearly able to see the difference; the powder from the untreated nucleus was pale yellow, while the powder from the treated one was bluish white.

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At the meeting of Gemological Institute of Japan 2001, Ms. Suzuki introduced that colors of fresh water pearls can be changed by heating.
Considering this result, we try to investigate the possibility of color change of sea water pearls and shells by heating.
The heating tests were actually executed by using Black-Lipped pearls and Black-Lipped shells this time. We observed and recoded the change of pearl and shells colors for the series of time.
Also, we paid a lot of attention to the change of UV-VIS-NIR Reflectance Spectra.

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Australia is one of the famous localities of opals. Lightning Ridge at the County of N.S.W. and Quilpie at the County of Queensland are well known as the Opal producing localities.
This time, we took an opportunity of examining an opal, which was supposed from Winton at Queensland. This is a matrix opal, which was studded with a black mother rock, has different appearance from a black opal and boulder opal. However by the color and the condition of constitution of it, some treatment might be done with it.
We took some testing and observations about this opal, and we report on our conclusion.

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Because the foreigner cannot enter the mine in Myanmar, information on the gem stones produced there has not been disclosed enough.
Moris Myanmar Co,. Ltd made the base of activity in Nam-Ya and we have kept researching. We report on information collected for six years.

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Consideration of effectiveness and the merchantability of heat treatment of Spinel.

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We report the recently encountered two clusters of synthetic alexandrite and emerald. This alexandrite was synthesized by Chatham in U.S.A. This emerald was synthesized by the laboratory at Novosibirsk in Russia.
These clusters could observe the other crystal as follows.
1) The synthetic alexandrite of the Chatham.
In the surface of the synthetic alexandrite, platinum and colourless synthetic phenakite are seen and in the bottom of its, the synthetic ruby is seen.
2) The synthetic emerald of the laboratory at Novosibirsk in Russia
The synthetic alexandrite identified by the X ray diffraction with cluster of this synthetic emerald.

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Taaffeite and Musgravite
Taaffeite and Musgravite are popular as collector's stones. It was difficult to distinguish Taaffeite from Musgravite by using the basic gemological methods until recently. Now, it is said that Raman microprobe spectroscopy and EDS (Energy Dispersive X-ray Fluorescence element analyzer) are useful for identification of them. This time we report a difference of them in a wave number of FT-IR.
Olmiite
Olmiite, which was known as Poldervaartite, was admitted as an independent mineral by IMA in 2006. So, we should differentiate between Olmiite and Poldervaartite. Olmiite's chemical formula is (Ca,Mn²⁺)₂[SiO₃(OH)](OH). Poldervaartite's is CaCa[SiO₃(OH)](OH). In other words, Olmiite is Mn2+ dominant analogue of Poldervaartite. But Ca²⁺ doesn't replace Mn²⁺ completely. We have to do the element analysis in addition to using the usual way to get a correct result.
We also describe green Microlite and Chkalovite.

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⋅ Both natural Shattuckite and natural Plancheite are produced in copper mine as secondary mineral. These two stones can be distinguished by the infrared and Raman spectroscopy.
⋅ Green amblygonite which has been circulated recently in the gem market is likely to be treated with the irradiation.
⋅ Natural orange kyanite has lately attracted attention as new variety of that species. It is considered that its colour is caused by manganese.

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Gemstone industry is now paying attention to the colour origin of andesine (whether it is natural or diffusion) and the authenticity of its geographic origin (where is real origin). To contribute to solving this problem, the author investigated mines in Tibet and Inner Mongolia of China in October and November, 2008. As the result, it was confirmed that Tibet produces red (rarely green) andesine while Gu Yang prefecture in Inner Mongolia only produces pale yellow andesine that was used for diffusion treatment as the starting material.

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Habit change is commonly observed in natural crystals. The origin of the habit change has not yet been understood theoretically, in spite of lots of experimental studies on the habit change. Crystal growth is the incorporation processes of growth units into kink sites on a surface. There are several parallel paths in the incorporation processes, among which the fastest path is a rate-determining. Kitamura and Nishioka (2000) revealed an existence of a rapid incorporation path in the case of high activation energy. In the present study, the concept of the rapid incorporation path is applied to analyze the origin of habit change among polyhedra bounded by planer surfaces whose growth is governed by the spiral growth mechanism. The analytical result shows that the habit change can occur when the activation energy increases. Particularly, a crystal consisting of the simple cubic lattice changes its habit from cube to octahedron as an increase of activation energies or supersaturation or an decrease of temperature.

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[in Japanese]

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In grading of diamonds, we must take care of treated diamonds such as HPHT and sometimes need advanced analytical techniques. One of the best techniques which can secern possibly treated diamonds from natural ones is FT-IR. FT-IR is very expensive and needs intelligent staffs, so is not suitable for separating from many diamonds. The machines selecting possibly treated diamond easily are D-Screen (HRD) and Diamond-Sure (DTC). Those machines need no intelligent staffs and are much cheaper than FT-IR. But those machines have problems, users cannot maintain machines and maintenance needs many time.
In order to solve such problems, I developed new machine that can separate diamonds possibly treated. The beginner of electrical handicraft can make it. Almost parts can be collect easily in electrical materials shop and the making cost is much cheaper than those machines. Maintenance is very easy and practical.
This presentation is how to make this machine and practicality of it.

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Colibri^TM was developed by Sarin Technologies Ltd. as automatic colour grading product for cape series diamonds. The characteristics and practicality of the Colibri^TM were examined by measuring about 15,000 pieces of diamond that had been graded by general routine work. As the result, it was confirmed that this instrument can be fairly useful as reference for objective colour grade on the majority of cape series diamonds when the instrument was properly used.

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For black opaque stones, many items including single crystals, rocks, and its stimulants have been known, and are difficult to be identified in many cases. In recent years, black diamond became popular and contamination with its stimulants, such as black cubic zirconia or synthetic black moissanite is given a problem. In addition, black spinel with coating treatment has been circulated in the gem market. To identify these stones, laboratory techniques such as X-ray radiography, fluorescent X-ray analysis or microscopic Raman spectral analysis are useful, in addition to standard gem testing method.

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