A method of the clarity grading of polished diamonds using the percentage of inclusions.

Colorless HPHT Synthetic Diamonds show remarkable phosphorescence. Boron contained in small amount is considered to be one of the factors. FTIR was used to estimate the boron concentration of the sample (uncompensated Boron). A fluorescence spectrophotometer was used to observe changes in the duration, intensity, and attenuation of phosphorescence. Phosphorescence is due to the recombination of nitrogen Donor – boron Acceptor pairs.

This time, the research from about 30 years ago to the present, we report on the current state of diversified cultured pearl nuclei, which was clarified by soft X-ray inspection of pearls and actual cutting of pearls and observation of the inside.

We investigated the correlation between bioactivity of Akoya pearl oyster and quality of produced pearls monthly. The amount of reserved glycogen in Akoya pearl oyster tended to increase and the genital organ in these tended to maturate toward winter, and producted pearls from these also were inclined to become hight-quality.

We have studied about crackes in nacreous layer which were caused during processing. This time we observed these after tested pearls we reported previously were more examined accelerated deterioration test, and we referred to the task ahead.

The Japanese name for minerals was a word coined in the Meiji era (ca.1875). And the Japanese name for gems dates back to the 16th century, but it has been used in the current sense since the Meiji era (ca.1889).

Paraiba tourmaline’s popularity is still unabated. In addition to Brazilian products, Nigerian and Mozambique products are on the market. The geographic origin determination of Paraiba tourmaline, focusing on observation with standard gemological instruments and X-ray fluorescence analysis is reviewed in this report.

Chemical Analysis of tourmaline using LA-ICP-MS is difficult because chemical composition of tourmaline is complex. In this study, we analyzed Paraiba- tourmaline using LA-ICP-MS based on some assumptions and studied the origin determination of Paraiba- tourmaline.