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.
The Sinkankas図書館（シンカンカスライブラリ） (英語)
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
Opals from Opal Butte, Oregon
Recent mining at Opal Butte in northeastern Oregon has produced a wide variety of large flawless opals.
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.
An Economic Review of the Past Decade in Diamonds
Detection of Treatment in Two Unusual Green Diamonds
A Gem-Quality Iridescent Orthoamphibole from Wyoming
Pastel Pyropes
An Update on Color in Gems. Part 3: Colors Caused by Band Gaps and Physical Phenomena
The final part of this series is concerned with colors explained by band theory, such as canary yellow diamonds, or by physical optics, such as play-of-color in opal.
Faceting Large Gemstones
Chrysoberyl and Alexandrite from the Pegmatite Districts of Minas Gerais, Brazil
Mining fine cat's-eye chrysoberyl and alexandrite in Brazil.
An Update on Color in Gems. Part 2: Colors Involving Multiple Atoms and Color Centers
This is the second part in a three-part series on the origin of color in gem materials.
The Gemological Properties of the De Beers Gem-Quality Synthetic Diamonds
The History and Gemology of Queen Conch "Pearls"
This article reviews the history of the conch "pearl," discusses S. gigas and its fisheries, and examines the gemological properties and other characteristics of this attractive material.
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