FROM THE LIBRARY
Garnet: From History to Modernity | Throughout history, January's birthstone – garnet – was used by Egyptian pharaohs, Roman rulers, European clergy and nobility. Garnet was most often used in jewelry, but historically also carved to make seals for official documents. In the 1500s, a large deposit of dark red pyrope garnets was discovered in central Europe, now the modern Czech Republic. The Central Bohemian Region is the most famous for garnet production, and in the trade the material mined from it was referred to as "Bohemian garnets." Since then, large varieties of garnets have been discovered, including in rare colors such as green and orange. Curious about garnet lore? | Courtesy of Gemfab CJSC. Photo: Britni LeCroy/GIA | FROM THE LAB
Planet Earth Turquoise | This 84.90 carat Armenian turquoise was recently donated to GIA. Polished into a sphere and with beautiful natural brown matrix, it bears an astonishing likeness to Planet Earth. Typically, turquoise without matrix is highly sought after, but this specimen is a fine example of how matrix can add character. Its color is natural but the stone has been treated to improve durability. Want to know what common treatment this turquoise received? | Photo by Annie Haynes. Gift of Mark Mauthner, GIA Museum no. 37511. | FROM RESEARCH
Eclogite: The Perfect Host | More than 99% of diamonds formed in the lithospheric mantle beneath continental plates, more than 300 kilometers underground. In the lithospheric mantle, there are two major diamond host rocks. GIA scientists recently studied one of them, eclogite—a metamorphic rock that can form from the subduction of dense oceanic crusts beneath the mantle. This particular specimen consists of iron-magnesium-calcium garnet and sodium-rich clinopyroxene, as well as a partially-exposed diamond crystal. Curious what scientists learned from studying this specimen? | We hope our gem knowledge inspires you to rock on. #knowledgerocks | |
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