Dual-Color Double Stars in Ruby, Sapphire, and Quartz: Cause and Historical Account
Examines a form of asterism comprising two six-rayed stars, one white and one that exhibits the stone’s bodycolor. Firsthand accounts and a survey of patent documents reveal that diffusion has been used to create or enhance this optical phenomenon in synthetic and possibly natural corundum since the 1950s.
Inside De Beers’ Lightbox Diamonds
GIA researcher analyzes and confirms that De Beers’ Lightbox diamonds are grown using the chemical vapor deposition process.
New Technologies and Techniques
Abstracts of speaker presentations from the “New Technologies and Techniques” session of GIA’s 2018 International Gemological Symposium.
Saltwater Pearls from the Pre- to Early Columbian Era: A Gemological and Radiocarbon Dating Study
Examines 85 saltwater natural pearls, reportedly harvested from the Caribbean islands off the coast of Venezuela during the early 16th century, to determine their age.
Synthetic Star Sapphires and Rubies Produced by Wiede’s Carbidwerk, Freyung, Germany
Details the process used by Wiede’s Carbidwerk to produce star synthetic corundum from the mid-1950s through the 1970s.
Characteristics of Gem-Quality By-Product Synthetic Zincite
Investigates the properties of synthetic zincite produced by industrial kilns in Poland.
Synthetic Emeralds Grown by Richard Nacken in the Mid-1920s: Properties, Growth Technique, and Historical Account
Describes the chemical, morphological, and microscopic properties of the first gem-quality synthetic emeralds ever produced, offering a historical perspective on their development.
Observations on CVD-Grown Synthetic Diamonds: A Review
Explores statistical data and defining characteristics of gem-quality CVD synthetic diamonds examined by GIA since 2003.
Large Colorless HPHT-Grown Synthetic Gem Diamonds from New Diamond Technology, Russia
Examines a new source of colorless and near-colorless gem-quality HPHT synthetic diamonds using spectroscopic and gemological analysis.
Update on Rock Creek Sapphire Deposit
An overview of recently expanded sapphire production at the Gem Mountain mine near Philipsburg, Montana.