Feature Article & Gem Notes

Experimental Study on Heat Treatment of Semitranslucent-opaque Sapphire from Chanthaburi, Thailand

Experimental Study on Heat Treatment of Semitranslucent-opaque Sapphire from Chanthaburi, Thailand

Chanthaburi, eastern Thailand, is one of the world-renowned gemstones producers. It is designated as a “City of Gems” as most of the world’s gemstones pass through the city.

February 28, 2022
The Study on CVD Synthetic Diamond from Various Producers

The Study on CVD Synthetic Diamond from Various Producers

In the past decade, the diamond industry has faced the new challenge of the synthetic diamond (aka Lab-grown Diamond) commercially available as gem grade and becoming a new natural diamond

February 28, 2022
Gemological Characterization of Peridot from Pyaung-Gaung in Mogok, Myanmar

Gemological Characterization of Peridot from Pyaung-Gaung in Mogok, Myanmar

The Pyaung-Gaung area in the Mogok township of Myanmar is one of the essential sources of high-quality peridot for the international gem trade. Pyaung-Gaung peridot possesses an attractive deep olive green

February 14, 2022
Gemmological and chemical characteristics of Yiqisong peridot, Jilin, People Republic of China

Gemmological and chemical characteristics of Yiqisong peridot, Jilin, People Republic of China

The significant deposit of gem-quality peridot has been found in the area called Yiqisong, Yanbian of Jilin province. At first glance, these peridots strikingly show a medium toned yellowish green attribute with high clarity.

August 27, 2019
Unique Orange Sapphire with Golden Sheen Effect Reportedly from Kenya

Unique Orange Sapphire with Golden Sheen Effect Reportedly from Kenya

Golden sheen sapphires from Kenya have been reported in this journal and elsewhere (e.g., T.N. Bui et al., “From exsolution to ‘gold sheen’: A new variety of corundum,” Journal of Gemmology, Vol. 34, No. 8, 2015, pp. 678–691; N. Narudeesombat et al., “Golden sheen and non-sheen sapphires from Kenya.

April 1, 2019
Phase Transformation of Epigenetic Iron Staining: Indication of Low-Temperature Heat Treatment in Mozambique Ruby

Phase Transformation of Epigenetic Iron Staining: Indication of Low-Temperature Heat Treatment in Mozambique Ruby

In the past several years, Mozambique has emerged as one of the world’s most important sources of ruby, and unheated stones from this country are in particularly strong demand. Nevertheless, it is common for these rubies to undergo low-temperature heating (~1,000°C or below) to slightly improve their colour.

July 11, 2016