Inclusions of native copper and tenorite (CuO) were found in grayish green elbaite from São José da Batalha, Paraíba, Brazil. Native copper forms strongly dendritic platelets (about 100 µ long, 1 µ ...

Amethyst may develop into the more common citrine and rarer green quartz naturally under certain geologic conditions. On the California-Nevada border, just north of Reno, amethyst, citrine, and green ...

Although lost for literally hundreds of years after the Spanish conquest of the Aztecs, many deposits of jadeite have been found in Guatemala during the last two decades. Following the discovery of ...

Jewelry-quality synthetic malachite is now being manufactured in the USSR. The texture, structure, and physical and physico-chemical properties of this synthetic malachite are reported. Three textural ...

Figure 1. This gold ring with a phoenix motif features a Neyshabur turquoise (13 × 17 mm), with a 0.02 ct ruby on each side and diamond accents. Courtesy of Taktala Jewelry, Tehran. Turquoise is an ...

Diamonds are the most amazing of gems. Just as amazing, however, is how natural diamonds reach Earth’s surface. Diamonds are formed 150 to 700 km deep in Earth, and are then carried upward in a rare ...

Originally published in GemGuide in 2016, this comprehensive series examines the quality factors that influence the value of colored gemstones, with a specific emphasis on the role cut quality plays ...

Metrology, the science of measurement and its application, plays a critical role in the accuracy of GIA’s research and laboratory services. The metrology team closely monitors the performance of ...

Figure 1. The 0.62 ct green “Matryoshka” diamond (4.8 × 4.9 × 2.8 mm) from Siberia has an internal open cavity connected by two small channels to the outside. The surface is covered by etched trigons ...

CARLSBAD, Calif. and HONG KONG – May 23, 2018 – Renowned jewelry group Chow Tai Fook Jewellery Group (“Chow Tai Fook”) and GIA (Gemological Institute of America), the leading independent diamond ...