Majorica Imitation Pearls
This article discusses the history of the Majorica imitation pearl, the manufacturing and marketing processes, and the separation of the Majorica product from its cultured counterparts.
Gem-Quality Cuprian-Elbaite Tourmalines from São José Da Batalha, Paraíba, Brazil
Unusually vivid tourmalines from the state of Paraiba, in north eastern Brazil, have attracted great interest since they first appeared on the international gem market in 1989.
Hydrothermally Grown Synthetic Aquamarine Manufactured in Novosibirsk, USSR
The Identification of Blue Diffusion-Treated Sapphires
Blue diffusion-treated sapphires are becoming more prevalent than ever before.
Jadeite of Guatemala: A Contemporary View
Many deposits of jadeite have been found in Guatemala during the last two decades.
Gem Localities of the 1980s
Gemstone Enhancement and its Detection in the 1980s
Zircon from the Harts Range, Northern Territory, Australia
Gem-quality zircon from a relatively underdeveloped locality in the Harts Range of central Australia is described.
Emerald and Gold Treasures of the Spanish Galleon Nuestra Señora de Atocha
During the 1970s and 1980s, treasure hunters discovered the centuries-old remains of the sunken Spanish galleons Nuestra Señora de Atocha and Santa Margarita.
The Capoeirana Emerald Deposit near Nova Era, Minas Gerais, Brazil
The Characteristics and Identification of Filled Diamonds
Grading the Hope Diamond
One of the most popular exhibits at the Smithsonian Institution, the stunning Fancy Dark grayish blue Hope diamond was formally graded by GIA’s gem laboratory.
Sinkankas 图书馆 (英语)
The world-renowned Sinkankas collection of books and other publications is now available to the public as part of the Richard T. Liddicoat Gemological Library and Information Center at GIA Santa Monica.
"Opalite": Plastic Imitation Opal with True Play-Of-Color
Amethyst Mining in Brazil
Gemstone Irradiation and Radioactivity
With the increasing use of radiation to color enhance gemstones, the issue of radioactivity has become a source of concern for gemologists worldwide.
Opals from Opal Butte, Oregon
Recent mining at Opal Butte in northeastern Oregon has produced a wide variety of large flawless opals.

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