We succeeded to synthesize pure polycrystalline diamond by direct conversion from graphite at very high pressure and high temperature using Kawai-type multianvil apparatus (KMA), which was found to be made of nano-sized crystals with peculiar fine textures and have extraordinary high hardness. Thus synthesized nano-polycrystalline diamond (NPD or "Hime-diamond") has following features in addition to its outstanding hardness: higher fracture toughness, higher thermal resistance, and relatively low thermal conductivity, etc., relative to single crystal diamond. NPD is highly transparent, but exhibits rather yellowish in color due to absorption of optical lights in shorter wave lengths, probably because of grain boundary scattering/absorption of sintered diamond crystals. Application of NPD to various high-pressure apparatus has been attempted, in addition to its industrial applications, yielding some promising results particularly in higher pressure generation using diamond anvil cell with relatively large culet size, X-ray absorption studies at high pressure combined with synchrotron radiation, and high pressure generation in multianvil apparatus. The techniques to synthesize NPD are also applied to synthesize high-pressure phases, yielding some novel polycrystalline materials, such as nano-polycrystalline stishovite, nano-polycrystalline cubic BN, and nano- to micro-polycrystalline garnets, some of which are highly transparent and named as "poly-crystalline gems (poly gems) ". Thus, the KMA has opened a new field of making novel functional ceramic materials utilizing its relatively large sample volumes and capability of generation of pressures far higher than 10 GPa and temperatures well exceeding 2500K.

View full abstract

Takahito Mori from Mori's Inc, Japan will make a research report on the appearance ratio of rubies rough stones at Mori's mine(2007-2011), Nam-Ya area in Kachin State.
We will also report the difference between the finish of the actual quality and the prediction made by the characteristics of the rough stones.

View full abstract

The engagement ring given Kate princess by British Prince William is blue sapphire.　　 It is mother of Prince William and is the same blue sapphire that I shined to the left hand of Princess Diana said to be the royalty wedding of the century. It was　Ratnapura product of Sri Lanka, and this blue sapphire was ever given to Queen Elizabeth by a jeweler of Ratnapura.
It is new in memory in good quality with a Sri Lankan in Kataragama 2011. Besides, that large drop of blue sapphire was produced.
The field investigated the four representative mines, Ratnapura of the Sabaragamwa prefecture, Parumdura　which produced high quality blue sapphire in Sri Lanka this time and Okkampitiya of the Uva prefecture, new mine lot.
As for the number of the mines of each district, the mosquito thallareed mace which became 50-60 places and the new mine lot in approximately 300 places, Okkampitiyain approximately 3,000 places, Parumdura in Ratnapurais mined now in 10-20 places.　　 I obtained a direct uncut stone from the mine of each mine lot to carry out the production center confirmation of the sample stone thoroughly and tried abrasion, ink roux John observation. Furthermore, by FTIR, I tried Fe, Ti, Ga, ingredient analysis of the Cr, fluorescence X analysis.
The purpose of this field work was to divide obtaining an examination for definite sample stone and the quality of each mine lot into Cem quality, jewelry quality, three phases of the accessories quality, and to investigate incidence of the blue sapphire of 3 quality each while heat treatment, Be heat treatment strode.
I evaluate the quality of the jewel, and the price jewel market price is fixed by incidence and demand for quality.
Because I investigate 4 mine lots including the new mine of the blue sapphire from Sri Lanka this time and carried it out, I report the place of origin situation.

View full abstract

Generally ruby is more evaluated than spinel as ruby is categorized in so-called “precious stone” and spinel is in “semi-precious stone”. However in the history of iconic royal jewelry, often spinel was used as ruby. From this aspect of history, isn't possible to think that spinel has made ruby as valuable and popular as it is now?
First, the “Black prince's ruby”, 170cts, has been used as ruby in the British crown jewelry, since it came into British Royal Family’s possession in 1367 until it was revealed to be spinel in the 19th century. Second, the red spinel of 398.72cts used in the crown of Catherine the Great, in Russia was also used as ruby. Third, the “Timur ruby” of 361ct had been also used as ruby in British royal collection until it was found to be spinel in 1851. These spinel had enchanted people as famous ruby of royal collection.
The red spinel was also called as “Balas ruby” in ancient time. Balas means Balascia, current Badakhsan. And these spinels are said to be from Kuh-i-Lal mine between current Tajikistan and Afghanistan.
On the other hand, not so many important rubies were used in royal jewelry. The Hixon ruby, the largest known ruby of 196.10cts is still in crystal shape. Also the Rosser Reeves Star Ruby of 138.7cts from Sri Lanka and the Delong Star Ruby 100.32cts from Myanmar are not set in royal or famous jewelry. The rubies used in royal jewelry are much smaller than spinel. For example, the Stuart coronation ring uses the ruby of 1.5cm x 1.3cm in size (Probably 10-15ct). Borghese ruby from Myanmar set in the parure for Princess Pauline Bonaparte is quite good quality but not so big as 2-3cts as estimated from its size. They are not impressive as the spinel mentioned above. Also, their origins are mostly Myanmar and some such as star rubies are from Sri Lanka.
As mentioned above, rubies used in important royal jewelry are sometimes spinels in fact. And those spinels aroused people"s adoration to ruby and increased the value of ruby itself. As Mr. Masashi Furuya expressed, ruby gained the status of today thanks to spinel. Spinel was the great pinch hitter in the gemstone history, we could say that spinel played a great rule in the history of royal jewelry.
Acknowledgments: Dr. Jack Ogden, Albion Art Co. Ltd.

View full abstract

There is a long acceptance that a spinel is non-treated gem. However． reports about the experiment on heating red-pink spinels from Myanmar and Tanzania． following the first laboratory work by GIA in 2005． suggest that there may have been heated stones circulated in the market.
The present report is of the experiment on heating natural (not-heated) pink spinels from Ratnapura． Sri Lanka at 1000 °;C for 5 hours in oxidizing conditions. Using EDXRF． Ultraviolet and visible spectrophotometer． Photoluminescence spectroscopy． and Spectro fluorometer． the results are diagramed for comparison of the changes before and after the treatment. One of the interesting results is that the graphic line of the heated stones show the same shape as that of flux synthetic spinels.
A spinel and a ruby have similar appearance and composition． and the places of their production are overlapped. The pink-red color of Cr-containing spinels comes from chromium as that of rubies does. Natural red spinels demonstrate "organ pipes"． the spectrometric Cr-lines peculiar to the stones． while a rubies show no such things. Then． we made another experiment on heating natural (not-heated) rubies from Mon Hsu． Myanmar on the same conditions with spinels above mentioned． and observed the changes before and after the heating in order to compare with the results of the experiment on spinels. Based on this comparison． we would like to consider the factors to change of Cr-lines of spinels induced by heating.

View full abstract

The occurrence of opal from Ethiopia has been reported in 1994 (Koivula J.I., et al 1994). Large opal deposits found in Wollo province at the first half of 2008 (Rondeu., et al 2010), large amount of cut stones are supplied to the gemstone market. But, it was also reported that export as rough gemstone has been prohibited in early 2013 (Addis Fortune Jan. 2013). Body color show range from colorless-white to pale yellow-brown and transparency show translucent to opaque. Weak blue UV fluorescence observed from almost Ethiopian opals, and it is different from Australian opals that show strong blue UV fluorescence and phosphorescence. Individual weight of Ethiopian opals can also change easily, because of the porous inner structure.
Black colored opals are supplied to the gemstone market from 2013, which is come from Ethiopia and similar to black opal. The seller indicates that these opals are treated by using the organic matter and acid. The prices of black colored opal are higher than not treated Ethiopian opal, and is estimated to simulate Australian black opal.
These stones show slightly brownish black body color with vivid play of color, it is different from the Australian black opal and the treated opal using smoke process and traditional sugar acid process. In addition, it seems that characterized by thickness of loose stones are quietly thick and absent of small loose stones. Transparent ray of black colored opal indicate dark red in color, and there are some black concentration as speckle or scratch mark. Cross section of black colored opal show color zonal structure, black matter are reached to core of stone, and surface show most dark color. Which indicate that the effect of the treatment is extend to the inside, and the treatment process need pre-form and re-polishing the surface after treatment. Origin of black color is reported as the presence of amorphous carbon (Williams 2012), we also confirmed the presence of amorphous carbon.
Dyed various color opal from Ethiopia began to supply since the beginning of this year.
We confirmed yellow-orange dyed opal which is similar to Fire opal, and Pink and blue dyed opal which are not exist in nature. Impregnation of colored resin was suspected, but results of near infrared spectroscopy analysis indicate that resin is not detected and use only dye to change color.
In this study, we reported characterization of treated black color opal and dyed opal from Ethiopia for gem identification, and progress of reproduction experiment and preliminary result.

View full abstract

The conventional color change in gemmology means the effect to change its color from green or blue green under day light (Illuminant D65) to red or purple red under the incandescent light (A illuminant). This mechanism is that such color change gemstones absorbs yellow light strongly and transmits green and red light contrastively. However there are some gemstones which change or seem to change their colors by other mechanism.
First, some gemstones change their color when strong light shines them from side. The pink sapphire from Batakundhi, Pakistan show blue color on the surface. This is one of the Rayleigh scattering. The micro inclusions scatter the blue light and it gives purplish tone to the stone. The similar effect can be seen with moonstone with blue schiller. In corundum, pink sapphire from Sri Lanka or ruby from Tajikistan also show some kind of phenomena. And this is also the beauty of Kashmir sapphire.
Second, color change with lighting with some direction can be seen with green andesine. Some andesine show green color with transmitted light, but is show red color on the surface with reflected light of same light source. When we measure the UV-visible spectra with transmission method and reflection method, the spectra differ as Figure.1 Such andesine has many micro inclusions of copper platelet. If the light transmits the stone, the copper platelet does not affect the color, only as a shadow. But if the light shines the stone, the light reflects from the copper platelet and cause orangish red color. Third, the recent scapolite from Afghanistan show very strong teneblescence. When the short wave UV is irradiated at this scapolite, the colorless stone changes its color to vivid violetish blue in 10 seconds. (Figure.2.) After it, it can be return to the original colorless color with strong light or heating in a few second. It also has reversibility.
As mentioned above, there are many gemstones change or seems to change its color not by conventional color change effect.

View full abstract

Authors have been investigating experimental estimation methods for grading of diamonds as cut jewels, which are regarded as transparent polyhedral materials constructed by plane facets. Interpretation that glare of the jewels is regarded as optical scattering by polyhedrons can suggest a way to physical and statistical analysis based on optical experiments.
Generally, grading of some jewels is achieved as optical observation by human's sense under recommended isotropic lighting environment since their brilliance is realized as external light. If so, recognized brilliance brought to human's eye should originate in both source of external incidence (from unidentified direction) and internal path in the samples. But, it is unfortunately too complicated to search or to trace the origin of incidence and inner path. Or, isotropic external lighting might not be necessarily suitable to quantitative evaluation.
The authors have noticed that the sample of the cut jewel as optical scatterer is shaped as polyhedron constructed by plane facets and that it is three-dimensional materials with linear ridgelines. Therefore, if the jewel sample is irradiated by incidence of straight and narrow-spread light (such as laser beam) which has sufficient width to cover the sample volume, (external and internal) reflection at the ridgelines divides the beam, and unidentified sequence of reflection makes the beam narrower.
Consequently, one straight incident beam to the polyhedrons is divided to scattered beams with various direction and much smaller widths. Or, the divided beams may be radiated (scattered) externally. If such beams scattered externally are detected by external some optical devices, that should just be “glare of jewels”.
Then, as the first step of our experiments with straight beam, the scattered beams are projected as “light spots” on a curved screen, and the scattered beams can be evaluated as the light spots with solid angles. And, the scattered light spots given by straight incidence are numerically evaluative through imaging analysis. Recognition of glare should be probability of scanning by the scattered light spots for region corresponded to virtual detectors; such probability is discussable with statistical distribution of number and size for the light spots.
Next, we can modify direction of incidence. When incidence moves with many enough steps as direction, it simulates “isotropic external lighting” approximately. Or, we can estimate emphasis of glare by anisotropic distribution in scattering. Then, data will be able to suggest what is more effective design for impressive glare under specific external lighting or what is better direction of observation for some designed jewels.
It is important that, in this discussion, we are not considering proportion of the sample; considered subjects are physical discussion: “how the beams are numerically divided when the sample is irradiated by a straight beam?” or “how projection of the scattered beams will change when incident direction is modified?”
As experimental equipment, we applied “parabolic (curved) screen” which had a focus adjusted to the measured sample. As straight incidence, laser beam or white LED light irradiated the sample through a slit equipped on the screen. “Light spots” from the sample projected on the screen were observed with a camera, and the images were analyzed as two-dimensional digital data.
And, for brilliant cut diamonds (58 facets) or ones with more or less facets, statistical distribution of solid angle (Ω) of scattered beams was analyzed. As a result; histogram of  showed “exponential rule” for numerical distribution in smaller Ω region: N(Ω)∝exp{-λΩ} (λ›0). However, since more impressive and intense glare may be attributed to light spots with larger Ω, we now suppose that deviation from the “exponential rule” may be important for jewel grading.

View full abstract

Two types of light interference phenomenon occur simultaneously in spherical shape of akoya pearls; interference caused by the reflection from, and the transmission through, nacreous layer. Also, when a pearl is brought into contact with a diffused light source such as a fluorescent lamp, the interference colors from all incident angles are observed in the higher and lower hemispheres.
It is empirically known from visual observations that the intensity of teri corresponds to 1) the number of expressed hues (hues), ii) the level of the saturation of expressed hues (chrome) and iii) the level of the luminosity of expressed hues (value).
Reflection and transmission interference colors induced by a special device were photographed and the color of the images ware analyzed.
There was a certain correlation between the results and the master pearls with five different teri intensities sorted by an experienced person.

View full abstract

Akoya pearls and silver-lipped pearls both have white-type, yellow-type and blue-type pearls, and methods for differentiating akoya and silver-lipped pearls have been studied for many years but it has not been established. Depending on the shell size and the sea area from which mother shells are harvested, oyster species have been estimated based on pearl size, the thickness of the nacreous layer ("maki"), pearl texture, among other things. In recent years, however, improvement of aquaculture techniques and other factors have enabled the market distribution of akoya pearls sized 10 mm or more and silver-lipped pearls sized 10 mm or less. Therefore, it is an urgent task to establish methods for differentiating akoya pearls and silver-lipped pearls.
Differentiation methods that have so far been reported are the ultraviolet laser excitation emission spectrum method (Komatsu et al., 1984) and the X-ray fluorescence analysis method (Ito, 2002). The former method measures differences in the spectral patterns of ultraviolet laser excitation between akoya and silver-lipped pearls, which are caused by the differences in organic substrates. However, such differences are erased by processes such as bleaching and thus the method has not been put to a practical use. The latter method uses an X-ray fluorescence analyzer to calculate the intensity ratios Sr/Ca and Na/Ca to differentiate akoya and silver-lipped pearls. Since a part of overlapping domain exists, it is not put in practical use.
In this study, by focusing on the differences in constituent elements and organic substrates between the two pearls, the following differentiation methods were performed.
First, using TOF-SIMS (Time of Flight Secondary Ion Mass Spectrometry), a method which measures the elemental composition and chemical structure of the top surface of pearls, the shells and pearls of akoya pearl and silver-lipped pearl oysters were analyzed. Second, LA-ICP-MS (Laser Ablation Inductively Coupled Plasma Mass Spectrometry) was used to compare the constituent elements between white-type akoya pearls and white-type silver-lipped pearls harvested in a particular sea area.

View full abstract

1. Background
Golden-lipped pearls have become increasingly popular due to their rarity and gorgeous appearance. However, in recent years, colored pears that elaborately imitate golden-lipped pearls have come into the market and it is an urgent task to develop methods for identificating these colored pearls from uncolored pearls. Conventional identification methods that have been used for golden-lipped pearls are the coloring mark observation method, the ultraviolet irradiation florescence observation method and the spectral reflection method. With the ultraviolet irradiation florescence observation method, it has been reported that colored pearls emit florescence and uncolored pearls ("natural pearls") emit only weak florescence. It has been suggested that the reason for natural pearls emitting weak fluorescence is that deep color natural pearls contain more yellow pigment in the nacreous layer, which blocks protein fluorescence. It has been reported that with the spectral reflection method, natural golden-lipped pearls show characteristic absorbances at 280 nm, 360 nm and 450 nm. However, due to the recent improvement of coloring techniques, coloring marks cannot be detected around holes anymore, and there are many cases where colored pearls do not emit fluorescence, making difference between natural and colored pearls difficult. In this study, as a new highly accurate non-destructive method for golden-lipped pearls, Raman spectroscopy was investigated.
2. Materials and methods
Colored and natural golden-lipped pearls were compared using the ultraviolet irradiation fluorescence observation method, the spectral reflection method and the Raman spectroscopy. Additionally, the pearl samples that were suggested by the results to be natural were cut into slices to determine if they were colored or uncolored pearls.
3. Results and discussion
With the ultraviolet irradiation fluorescence observation method, some colored pearls were observed to emit fluorescence (e.g., red or blue and white color under short-wave or long-wave ultraviolet), whereas other colored pearls did not emit fluorescence just like natural pearls do not; it was therefore suggested that the identification would be difficult with this method.
With the spectral reflection method, one or more of the three absorbances characteristic to natural golden-lipped pearls were not observed or shifted in colored pearls. A problem with this method is that pearls are influenced by reflection interference colors because pearls are multilayer spheres. When a pearl is set in the integrating sphere of a spectroscopic analyzer for measurement, normally the body color of the surface is measured; however, if teri is strong, measurements are strongly influenced by reflection interference colors. Therefore, when analyzing pearls with strong teri, natural pearls may lose their characteristic absorbances, resulting in their being misjudged as colored pearls.
On the other hand, with the Raman spectroscopy, significant differences were found between colored pearls and natural pearls, with the former showing the scattering intensity of 5,000 or higher and the latter showing the scattering intensity of 5,000 or lower, suggesting that this method can be used for identificating the two purposes. Also, because some colored pearl samples showed similar spectral data to natural pearls, the slices of the colored pearls were observed under an optical microscope. The observation confirmed no colored layer on the outer layer, confirming that they were natural pearls. Therefore, it was suggested that Raman spectroscopy was a highly reliable non-destructive method.

View full abstract

Artificial stratification was produced by a multilayer film manufacture method with the aragonite (CaCO₃) of corbicula and polyvinyl alcohol (PVA) as starting materials .
The product shows pearly luster. The structure like a nacreous layer is observed by electron microscopy. This multilayer film manufacture method is as follows.
1. Crush a shell of corbicula with a vibration mil after burning at 300°C and concuss it using a supersonic wave in dilute ethanol solution for 20 minutes.
2. Take out a surpernatant including particles less than 10µm by centrifugation.
3. Drop this surpernatant on glass substrate.
4. After it heated to 80°C on a hot plate, it is evaporated to dryness.
5. Drop PVA 1 wt% on the substrate upon a glass, and coated with a spin coater.
6. Drying for 15 minutes.
7. Heat to 180°C for 1.5 minutes on the hot plate.
8. Repeat operations from 3 to 7.
We report the results of these examinations.

View full abstract

From Manyo era, it was known that natural pearls often can be found in Akoya oysters in Japan.　And really tiny pearls were called "keshi"　which came from a word " keshitsubu　(poppy seed) ".　Of course, all of " keshi" were natural pearls in old days. "Keshi" was already classified according to the literatures of ancient times, based on its appearance and the location of the oyster which was found.　About 100 years ago, pearl farming by Akoya oyster had succeeded commercially in Japan.　From oysters that were cultivated, very small pearls were collected and distributed in the vicinity of adductor muscle and mantle as a by-product to the cultured pearl.　Those small pearls have been called " Keshi".　Relatively large pearls in baroque shape which does not contain a nucleus could be found, during the farming process of Akoya pearls.　This has also been in the category of " Keshi " .
From these situations, "Keshi" has been treated as a cultured pearl now, and its recognition is changing with the times.
This time, we investigated the internal structures of " Keshi" pearls which were collected from the existing domestic Akoya pearl farms.　Over 100,000 samples were kindly provided by the pearl farms in Kumamoto Prefecture Amakusa Reihoku, Ehime Prefecture Uwajima Akehama, and Iki, Nagasaki Prefecture.　As a result, we found there are various internal structures in keshi pearls. We report on the various internal structures of the keshi pearls using the soft X-ray transmission image in particular.
Over 10mm size sea water baroque shape no nucleus pearls of white and black south sea cultured pearls have been traded from about 25 years ago.Even over 20mm sea water baroque shape no nucleus pearls have emerged nowadays.
Using the soft x-ray investigation, similar cavity among these pearls were found and the use of jelly or paraffin made nucleus is also reported.　We have started knowing that the diversity of farming technology has made the certain limit in the inspection task of sea water baroque shape no nucleus pearls.
We will consider how to call large size " keshi" in both traditional no nucleus pearls and innovated ones.

View full abstract

Identification of CVD-grown or HPHT-grown synthetic diamonds requires advanced laboratory techniques using such as photoluminescence spectroscopy or DiamondView™ in addition to the standard gemological tests. In this report we introduce examples of natural type II diamonds that show pseudo-synthetic features superficially resembling synthetic stones in such advanced analyses.
(1) All the colorless to nearly colorless CVD-grown synthetic diamonds of fifty-four samples in total that had been submitted to our laboratory since 2012 showed a Si-V peak at 737 nm (736.4/736.8 nm) in photoluminescence spectra. On the other hand, nine samples of natural type II diamond that had been analyzed around the same time showed the Si-V luminescence peak. This was accompanied by many other peaks including the one at 714 nm, and together with the existence of included minerals this indicates natural origin of the stones.
(2) Distinct sector zoning that shows greenish blue color luminesce and phosphorescence has been observed by DiamondView™ in two type II diamonds, which were submitted by different clients independently. This is generally a characteristic feature seen in HPHT synthetic diamonds, but cloud inclusions observed under magnification revealed that these samples were natural diamonds containing CO₂ that gives rise to characteristic peaks in FTIR analysis.

View full abstract

1. Introduction: Previous formations of large to micro diamonds are studied on solid-changes of carbon-rich starting materials of graphite or fullerene. The purpose of this study is to elucidate dynamic process of micro to nano-diamonds including material state changes [1, 2].
2. Micro-diamond carbon by artificial explosive formation: Artificial micro-diamond formed by explosive process (as dynamic standard) shows clear shapes with carbon-rich composition (and Si etc.) obtained by the FE-SEM data and micro-Raman spectral patterns..
3. Natural micro-diamond carbon from Yamaguchi, Japan: Natural formation of carbon-rich samples with mixed compositions are found at volcanic basalt on Shimonoseki, Yamaguchi, Japan, which are checked so far by the FE-SEM (as carbon-rich) and micro-Raman spectral pattern (as diamond main peak) .
4. Discussion: Gem-crystals of diamonds can be also related with shallow carbon sources of carbonatite (or calcite) by reaction within ring dikes, where are compared with artificial impacts [2] and volcanic breccias of Arkansas (U.S.A.) diamonds. Localized carbon-bearing breccias at the interior triggered initially by shock wave process can be formed at shallow sites during long geological history.
5. Summary: Diamond-like carbon grains were found at volcanic basalts of Yamaguchi, Japan, which are studied by the micro-Raman and FE-SEM.

View full abstract