“Larimar” is known as gemstone variety of pectolite. It contains small amount of Li2O. In this study, I perform quantitative analysis using XRF and LIBS, and determine detail chemical composition of “Larimar” from Dominica.

The pink jadeite from Myanmar is quite similar to the lavender jadeite. They are all colored by minor trace element of Mn. However, the pink one contains even less Fe, which may shift of the absorption peak from 570nm to 540nm to cause the pink tint.

Sapphire is a widely heated gemstone. In the current jewelry market, in addition to the traditional simple (low temperature) heating, Chemical diffusion from an external source and heating with pressure are mixed and distributed. Every time such a heating technology is newly introduced, international controversy has been happened and new regulation has been established. In this report, heat treatment of sapphire is reviewed.

At the National College of Technology, chemistry experiments guarantee a certain level of quality for all students, regardless of department. However, in departments such as mechanical and information systems, chemical experiments are not directly linked to specialized fields. Therefore, those students have little interest in chemical experiments. On the other hand, diamond is familiar to information systems as a thin film for substrates, and phosphophyllite is familiar to mechanical systems as a rust preventive film. Therefore, I was interested in materials that are familiar to their specialized fields with the keyword of jewels, and constructed a simple synthetic experiment.

Chameleon diamonds have the characteristic of photochromism and thermochromism. The stable color is a low-saturation color such as gray-yellow-green, and after the change, it changes to a high-saturation yellow, but it returns to the stable color with the passage of time or when heating is stopped. The cause of this discoloration has not been clarified, but common optical properties to chameleon diamonds have been reported. These characteristics were verified for the sample chameleon diamonds. One of the characteristics of chameleon diamonds is yellow phosphorescence. When fluorescence and phosphorescence were measured using fluorescence spectroscopy, luminescence with a peak of 550 nm was confirmed.

We tried to apply a deep learning technique to the diamond clarity grading. CNN algorithm with around 65000 diamond images which graded by professional graders in advance leads to the result that over 80% samples were correctly predicted, which shows the validity of this technique.

A method (ver.2) of the clarity grading of polished diamonds using the percentage of inclusions.

The former Japanese name for gems was a word coined in the warring states period (ca.1590).

At that time, gems were used in a different sense than today. The Japanese name of gems adopted the Chinese Honzo Komoku. This book can study natural history at that time.

An analysis of an anecdote of the “Orphan Pearl” in the 10th century Arabic literature reveals low yields of pearls of Pinctada margaritifera and the employment situations of the pearl fishery in the Arab world at that time.

In recent years, the nucleus of cultured pearls has diversified. The soft X-ray inspection can obtain information on the inside of pearls without cutting the pearls. Therefore, this time, we will report an example of effective use of soft X-ray fluoroscopy for pearl identification.

We offered to repair pearl products which were suffered damage from a flood in Kumamoto prefecture in July, 2020. Therefore we researched what kind of deterioration of pearls were there. We observed damaged pearls with optical fiber and microscopy.

We observed the structure of three kinds of pearls which were cultured in Nagasaki Pref. this year. And we investigated there factor and occurring time.

In order to try for origin determination of pearl using LA-ICP-MS, we analyzed changes through the treatments of pearls and differences between the origin ‘Uwajima, Ehime’ and ‘Iki, Nagasaki’