Brazil is currently the leader in overall production of amethyst. This article describes the author's visits to three of Brazil’s most important mining areas: Marabá, Pau d’Arco, and Rio Grande do Sul ...

Since late 2007, rubies and sapphires have been mined by hand methods from both eluvial and primary deposits at Winza in central Tanzania. The gem corundum is related to “dikes” of amphibolitic rocks ...

Zimbabwe’s Sandawana mines have been an important producer of emeralds for 40 years. Since the mines came under new ownership in 1993, consistent production has been established and, in addition to ...

Large quantities of rubies—both rough and faceted—from a commercially important new source in Myanmar (Burma) have been available on the Bangkok market since 1992. The ruby crystals from the Mong Hsu ...

For over 200 years, the only known source of imperial topaz has been a small mining district near Ouro Preto. One of the oldest and most productive mines in the district is the Capão do Lana. This ...

Although Afghanistan has historically been well known for its lapis lazuli deposits, significant amounts of fine emerald, tourmaline, kunzite, and some rubies are now emerging from that embattled ...

A necklace of round beads offered as "blue quartz from India" was analyzed by gemological and additional advanced techniques. The violet-blue ornamental material, which resembled fine-quality lapis ...

The authors have encountered hundreds of polymer-filled aquamarines in the Chinese jewelry market. This treatment can be identified with a standard gemological microscope, since it has characteristics ...

This article examines the sophisticated techniques and equipment currently used to fashion a polished gem from a rough diamond. The basic manufacturing techniques— sawing, bruting, blocking, and ...

Adjacent amethyst and citrine colors in the same crystal of quartz have been reported from South America, although there appears to be uncertainty as to the exact locality of origin. Such material has ...

Soon after it was first marketed in 1976, colorless cubic zirconia became the dominant diamond imitation, with current production of approximately 60 million carats per year. Although cubic zirconia ...

In recent years, significant amounts of gem-quality sodalite/hackmanite—some unusually transparent—have been produced from the Mogok region of Myanmar and Badakhshan Province in Afghanistan. Samples ...