Fossa Magna Museum in Itoigawa City has been struggling to keep up with the increasing demand for its stone identification service. To address this issue, a study was conducted to develop a jade identification device using photographs of shore pebbles. The stones used for learning were pebbles collected along the coast of Itoigawa, with jade pebbles collected with the cooperation of museum staff. The study made use of the TensorFlow machine learning software library developed by Google and the image classification and object recognition architecture NASNet for transfer learning.

After allowing NASNet to study around 13,000 photographs of stones, the software achieved a successful identification rate of 96% for jade and non-jade stones when working with the teacher data. The engine achieved a 95% success rate when identifying 20 photographs of jade and a 100% success rate when identifying 13 photos of non-jade stones. The study shows that the identification of jade and non-jade stones is possible using artificial intelligence and deep learning. Future research will focus on improving identification rates through the provision of additional teacher data, teaching the engine to recognize each rock type, and trials in using smartphone photography to provide image samples.

We perform to use deep-UV LED for UV fluorescence observation unit. It can use shortwave UV light source instead of UVC mercury lamp. There are several difference of fluorescence color.

Amethyst crystals from Mitsuiwa-moutain, Nanmoku Village were reported. Druses in black clay between limestone and green schist included amethyst, inclusion-bearing quartz and the aggregation of small quartz crystals.

Fluorescent opals produced in Shikaribetsu, Hokkaido were classified into three types according to their fluorescent colors, and biomarker analysis was performed to clarify the organic matter that is the source of each type of fluorescence.

In this study, we have shown that the UV fluorescence (FL) of opal from Shikaribetsu area, Shikaoi-cho, Hokkaido, is due to the presence of polycyclic aromatic hydrocarbons (PAHs). The opal, which exhibits a variety of color FL upon irradiation with long-wave UV, was crushed, chloroform-extracted, and analyzed for soluble components by HPLC. And luminescent component was found to be PAHs with a molecular weight of 150 to 400. Orange FL is due to finely dispersed bitumen in opal, and yellow to yellow-green FL is due to crystalline PAH inclusions such as coronene (Cor) and benzo[ghi]perylene (BPer) crystals. Crystalline Cor is carpathite, and crystalline BPer is a new mineral, approved by International mineralogical association in 2023 as hokkaidoite.

We analyze some light-blue minerals that appear to be chrysocolla associated azurite and malachite. However, the results of EDS show that these light-blue minerals cotain a high concentration of Mg that should not be present in chrysocolla. Combining the experimental results of FTIR, Raman Spectra, and XRD, we believe that these minerals are actually talc.

Jadeite jewelry is sometimes found as “Magatama” which is a comma-shaped bead, we called a type of "Gyoku", at sites dating from the Jomon period (about 14,000 BC to the 10th century BC). In the ancient Japanese book "Kojiki" (712), "Gyoku" is mentioned as one of the "Three Sacred Treasures", but its true identity has not been revealed. At Kotaki in Niigata Prefecture, Japan, the jadeite (Kono, 1939) and the other jadeites (Chihara, 1974, Hayashi et al., 2016, etc.) have also been reported. "Blue Gyoku" described in the Chinese "Three Kingdoms" (280-297) may have been found at Kotaki.

We analyzed rubies from Greenland and blue sapphires from Montana, USA with LA-ICP-MS and compared with ones from other localities. Greenland rubies and Montana sapphires can be distinguished from other sources using trace element analysis.

Fluid inclusions of carbon dioxide are well known as typical naturally occurring inclusions in corundum. (Koivula 1980). Until recently, they are also considered evidence of absence of thermal treatment, but carbon dioxide fluids have been reported even after heating with pressure (Nattida Ng-Pooresatien 2020) and they are no longer absolute evidence of absence of thermal treatment. Previous reports of carbon dioxide fluid have been determined by observation under a microscope, but in this presentation we report that infrared absorption can be used to confirm the presence of carbon dioxide fluids in corundum.

Samples of Star Peridot mined in Mogok, Myanmar were examined. While in previous studies the cause of asterism was described as magnetite inclusions, it is fine colorless acicular inclusions in two directions. One direction has longer thicker needles than the other. Since the needles can show some iridescence, they may be hollow tubes, possibly with a filling of magunetite or serpentine.

Peridot, the gemological term of olivine, has been one of the most commercially important gemstones throughout history. Gem-quality olivine is classified into three types based on geological genesis: basalt-related (igneous) type, metamorphic/hydrothermal type and extraterrestrial origin. We compared FTIR spectra and trace element chemistry of peridot samples from various sources including Burma, Pakistan, Egypt and Norway to distinguish them. Hydroxyl in olivine can be detected as absorption bands in FTIR spectra and is considered to be associated with defects within olivine structure. The types of defect are related to the geological origin of peridot and classification of defect types using FTIR can be helpful to distinguish them. In addition, chemical analysis using several key elements such as Mg, Ni, Fe and B are helpful to separate peridots from various sources. FTIR and trace element chemistry can be used to determine geographic origin of metamorphic/hydrothermal peridot. On the other hand, determining origin of basalt-related peridot is challenging for now because they show similar defect types and overlapping chemistry.

Laboratory Manual Harmonisation Committee (LMHC) recently updated the definition of Paraíba tourmaline by adding extra descriptions. One of them is about o-ray polarized spectrum to consider some Fe-rich cuprian tourmalines. However, absorption spectra can be incorrect depending on the gemstones’ facetted nature and transparency conditions. Simple comparison of absorption intensities at approximately 700 nm and 900 nm might cause misleading results. Because the definition is based on Cu and Fe, accurate absorption intensities by these elements is necessary. This study suggests a judging method of which element is the dominant chromophore basing on the simulation with trace element concentrations.

Fe doped MgAl₂O₄ crystals have been grown using floating zone technique. Crystals were grown from various Fe concentrations and compositions (x=MgO/Al₂O₃ molar ratio) under various O₂ concentrations. Crystals in pink were grown from 100 vol% Ar atmosphere.

The alkali-silica reaction is a phenomenon in which silica contained in concrete reacts with alkali. The reaction causes deterioration of concrete structures, and opal in particular is known as a dangerous reactive mineral. Authors propose a cross-disciplinary approach between chemistry experiments and materials systems engineering by incorporating the verification of degradation by alkali-silica reaction into opal synthesis experiments.

In this report, we overgrown CVD synthetic diamonds on natural diamond substrates with a target thickness of 2000 μm, explored the possibility of commercial practicality, and performed gemological observations after cut-polishing.

The color enhanced diamond producers Lotus Colors, Inc and Briza Color diamond companies based in New York, USA has started to provide various irradiated and HPHT treated beautiful colored diamonds since 1993. In this study, the characteristic of Lotus diamond will be introduced and a comparing experiment result has been collected by advanced spectroscopic analysis.

Structural colors of pearls depend on periodic structures of aragonite crystal layers and conchiolin sheets. Transmission and reflection spectra of Akoya pearls are calculated using Maxwell’s equations. The texture of Akoya pearls is reproduced by the cube mapping method.

Penguin's wing oyster (scientific name: Pteria penguin 〈Röding,1798〉 ), which belongs to the Pteriidae family, is one of the mother shells of half-shaped pearls used as a material for jewelry. Currently, Penguin's wing oyster produces not only half-shaped pearls but also nucleated pearls (perfect circles), and diversity can be seen as a commercial material. As a by-product of aquaculture, these mussels sometimes produce sparsely sized and baroque-shaped nuclear-free pearls. These are conventionally called Keshi pearls in the Japanese pearl industry. The problem is that it is difficult to distinguish them from Keshi pearls produced from other mother shellfish because they have a variety of appearances in terms of size, shape, and color tone. In this study, we introduce the Keshi pearls produced from these Penguin's wing oyster and also report on the search for a method of distinguishing them from Keshi pearls produced from other mother shellfish.

Pearls express fluorescence by the UV irradiation. Observing the fluorescence of the pearls is used as one of the methods of the identification. Unprocessed akoya pearls express yellowish fluorescence, while bleached akoya pearls exhibit a bluish-white color. This suggests that the protein in the nacreouse layers is affected somehow by bleaching process.

In this study, we investigated the changes in the fluorescence of processed pearls using 3D fluorescence spectroscopy

Recently, south sea pearls have shown the characteristics not seen before. For example, different fluorescence color and intensity, and "processing flaws" that are mainly seen in akoya pearls. Therefore, it is thought that new and different processing is now taking place in south sea pearls. In this study, we focused on south sea pearls that emit blue-white fluorescence similar to bleached akoya pearls.

Recently small-sized nucleated fleshwater pearls came to circulate in the market.These pearls similar to akoya pearls. So we summarized the differences of characteristics between nucleated freshwater pearls and akoya pearls.

We observed that many of these pearl’s holes had collapsed. For this reason, we thought that nacreous layers of nucleated freshwater pearls became weak by the process. We also investigated these cause in terms of nacreouse layer’s structure.

Nowadays freshwater pearl’s entry into a pearl market is remarkable. At one time, many of freshwater pearls were non-nucleated and show distorted shape but nucleated freshwater pearls show nearly round. Freshwater pearls which possess high quality of colour and luster in parallel with marine pearls, can be seen. Moreover, freshwater pearls which emit metallic strong luster beyond pearly luster and show unique beautifully shinning appearance accompanied with rainbow interference colours, can be found very rarely. I introduce this pearl here and report the results by gemmological tests and chemical analysis in the characteristic pearls.

Nacre thickness is an important quality factor in nucleated cultured pearl. In general, pearls with thin nacre thickness are less beautiful. However, pearls with extremely thin nacre are recognizable at first glance but appearance and the numerical value of nacre thickness are not always coincident in case of pearls with certain nacre thickness. In addition, when we consider the durability of nucleated cultured pearl, the nacre thickness is important. In fact, the damages such as breakage, crack and peeling can be seen often on pearls with thin nacre thickness. Based on the above, I measured the nacre thickness of pearls looked like thin nacre or damaged, then investigated a relationship between nacre thickness with beauty and durability. Furthermore, I considered how it relates to the nacre volume ratio which was a newly proposed parameter for nacre thickness taking pearl diameter and nucleus size into account.