The Color Origin of Gem Diaspore: Correlation to Corundum
Examines the color origin of color-change diaspore, known commercially as Zultanite, and compare the effectiveness of the chromophores it shares in common with corundum.
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.
Carbonado Diamond: A Review of Properties and Origin
Presents a detailed examination of about 800 samples of carbonado diamond from Brazil and the Central African Republic, including possible models for its genesis.
Causes of Iridescence in Natural Quartz
Describes the occurrence of iridescence, and the role of differential etching, in quartz crystals from India’s Jalgaon District.
Chrysoberyl from the New England Placer Deposits, New South Wales, Australia
Examines a collection of chrysoberyl samples from these sapphire placer deposits to determine their distinct mineralogical and chemical properties.
Colombian Trapiche Emeralds: Recent Advances in Understanding Their Formation
Proposes a model for trapiche emerald formation based on petrographic, spectroscopic, and chemical examination.
Amethyst from Boudi, Morocco
An introduction to Moroccan amethyst, which features distinctive color zoning and inclusions.
Fall for Autumn Gems
Nature gives us a brilliant palette of color-changing leaves and a spectacular kaleidoscope of colorful sunsets during the fall season.
Pseudo-Synthetic Growth Structure Observed in Natural Diamond
This stone was a good example of a very rare natural diamond exhibiting synthetic growth characteristics.
Rare Double-trapiche Emerald
At the AGTA show, Equatorian Imports showed this contributor two pieces of emerald with a very rare double-trapiche pattern